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THE  ANALYSIS  OF  SENSATIONS 


THE 
ANALYSIS  OF   SENSATIONS 

AND   THE    RELATION   OF   THE 
PHYSICAL  TO  THE  PSYCHICAL 

BY 

DR  ERNST  MACH 

EMERITUS   PROFESSOR  IN  THE  UNIVERSITY  OF  VIENNA 


TRANSLATED  FROM  THE  FIRST  GERMAN  EDITION 

BY 

C.  M.  WILLIAMS 


REVISED  AND  SUPPLEMENTED  FROM  THE 
FIFTH  GERMAN  EDITION 

BY 

SYDNEY  WATERLOW,  M.A. 


CHICAGO  AND  LONDON 

THE  OPEN  COURT  PUBLISHING  COMPANY 
1914 


c         ** 


Copyright  in  Great  Britain  under  the  Act  of  1911 


TRANSLATOR'S  NOTE 

THIS  book  is  not  so  much  a  new  edition  of  the 
English  translation  of  Professor  Mach's  Contri- 
butions to  the  Analysis  of  the  Sensations^  which  was 
published  in  1897, 1  but  is,  as  the  more  comprehensive  title 
indicates,  an  almost  entirely  new  book.  The  Contributions 
originally  appeared  in  1886.  The  English  translation  of 
1897  contained  a  certain  amount  of  new  matter,  most  of 
which  was  embodied  by  Professor  Mach  in  his  second 
edition  (1900).  Since  then  there  have  been  three  more 
editions  :  two  of  them,  the  third  and  the  fifth,  containing 
important  changes  and  additions  of  such  extent  that  the 
fifth  edition,  of  which  this  translation  is  now  offered  to  the 
English-speaking  public,  is  a  book  nearly  twice  as  long  as 
the  original  English  translation. 

It  may  therefore  be  convenient  to  mention  here  the 
principal  respects  in  which  this  book  differs  from  the 
translation  of  1897.  Six  chapters  are  entirely  new, 
namely,  Chapter  III.,  on  "My  Relation  to  Richard 
Avenarius  and  other  Thinkers  " ;  Chapter  V.,  on  "  Physics 
and  Biology :  Causality  and  Teleology  " ;  Chapter  VIII.,  on 
"  The  Will "  j  Chapter  IX.,  on  "  Biologico-teleological  Con- 
siderations as  to  Space  " ;  Chapter  XI.,  on  "  Sensation, 

1  Contributions  to  the  Analysis  of  the  Sensations,  by  Dr.  Ernst  Mach. 
Translated  by  C.  M.  Williams.  Chicago  :  Open  Court  Publishing  Co., 
1897- 

5C547B 


vi  THE  ANAL  YSIS  OF  SENS  A  TIONS 

Memory  and  Association,"  and  Chapter  XV.,  on  "  How  my 
Views  have  been  received."  Further,  the  eight  chapters  of 
the  original  edition  have  all  been  greatly  expanded.  Chapter 
II.  now  contains  most  of  the  matter  which  appeared  as  an 
appendix  to  the  translation  of  1897.  Chapter  VII.  contains 
six  sections  by  Dr.  Josef  Pollak  on  recent  research  as  to 
the  functions  of  the  labyrinth  of  the  ear. 

It  will  be  seen  that  the  changes  and  additions  fall,  on 
the  whole,  into  two  classes.  They  are  made  with  the 
object  either  of  amplifying  and  bringing  up  to  date  the 
author's  original  discussions  of  points  of  detail,  or  of 
explaining  and  justifying  his  more  general  views  as  to  the 
relation  between  different  branches  of  science  and  as  to 
questions  on  the  borderland  between  science  and  philo- 
sophy. It  ill  becomes  a  translator  to  indulge  the  temptation, 
which  he  yet  must  feel,  to  turn  commentator  or  eulogist ; 
but  I  may  perhaps  be  allowed  to  point  out  the  great 
interest  attaching  to  the  explanations  here  given  by  the 
veteran  physicist  and  philosopher  (if  Professor  Mach  will 
allow  the  word  "philosopher")  of  the  way  in  which  his 
views  were  developed. 

For  those  parts  of  the  text  which  are  identical  with  the 
English  edition  of  1897  I  have  availed  myself  largely  of 
Miss  Williams's  excellent  translation.  Finally,  I  must  add 
that  the  whole  of  the  present  translation  has  been  most 
kindly  read,  in  manuscript,  by  Professor  Mach  himself. 


SYDNEY  WATERLOW 


28  JOHN  STREET,  BEDFORD  Row, 
LONDON,  W.C. 


AUTHOR'S  PREFACES 

PREFACE  TO  THE  FIFTH  EDITION 

r  I  AHE  text  of  this  edition  has  been  enlarged  by  a  number 
-L  of  new  passages  and  notes.  There  is  an  insertion 
of  some  length  on  recent  investigations  as  to  the  sense  of 
orientation ;  this  is  from  the  pen  of  Professor  Josef  Pollak, 
who  has  also  been  so  kind  as  to  read  the  proofs  of  the 
whole  book  and  to  correct  the  index.  For  all  these  services 
I  owe  him  my  heartiest  thanks.  A  mistake  as  to  Ewald's 
theory  of  audition  has  been  corrected.  I  have  noted  with 
satisfaction  that  a  view  of  the  relation  between  the  physical 
and  the  psychical,  which  is  almost  identical  with  the  view 
advocated  here,  occurs  in  a  book  by  Alfred  Binet  (DAme 
et  le  Corps,  Paris,  1905). 

VIENNA,  May  1906 


PREFACE  TO  THE  FIRST  EDITION 

THE  frequent  excursions  which  I  have  made  into  this 
province  have  all  sprung  from  the  profound  con- 
viction that  the  foundations  of  science  as  a  whole,  and  of 

vii 


viii         THE  ANALYSIS  OF  SENSATIONS 

physics  in  particular,  await  their  next  greatest  elucidations 
from  the  side  of  biology,  and  especially  from  the  analysis 
of  the  sensations. 

I  am  aware,  of  course,  that  I  have  succeeded  in  con- 
tributing but  little  to  the  attainment  of  this  end.  The  very 
fact  that  my  investigations  have  been  carried  on,  not  in 
the  way  of  a  profession,  but  only  at  odd  moments,  and 
frequently  only  after  long  interruptions,  must  detract 
considerably  from  the  value  of  my  scattered  publications, 
or  perhaps  even  lay  me  open  to  the  silent  reproach  of 
desultoriness.  So  much  the  more,  therefore,  am  I  under 
especial  obligations  to  those  investigators,  such  as  E. 
Hering,  V.  Hensen,  W.  Preyer  and  others,  who  have 
directed  attention  either  to  the  matter  of  my  writings  or  to 
my  methodological  expositions. 

The  present  compendious  and  supplementary  present- 
ation of  my  views  will,  perhaps,  place  my  attitude  in  a 
somewhat  more  favorable  light,  for  it  will  be  seen  that  in 
all  cases  I  have  had  in  mind  the  same  problem,  no  matter 
how  varied  or  numerous  were  the  single  facts  investigated. 
Although  I  can  lay  no  claim  whatever  to  the  title  of 
physiologist,  and  still  less  to  that  of  philosopher,  yet  I 
venture  to  hope  that  the  work  thus  undertaken,  purely  from 
a  strong  desire  for  self-enlightenment,  by  a  physicist 
unconstrained  by  the  conventional  barriers  of  the 
specialist,  may  not  be  entirely  without  value  for  others 
also,  even  though  I  may  not  be  everywhere  in  the 
right. 

My  natural  bent  for  the  study  of  these  questions  received 
its  strongest  stimulus  twenty-five  years  ago  from  Fechner's 
Elemente  der  Psychophysik  (Leipzig,  1860),  but  my  greatest 


A  UTHORS  PREFA  CES  ix 

assistance  was  derived  from  Bering's  solution  of  the  two 
problems  referred  to  on  pages  69  and  168. 

To  readers  who,  for  any  reason,  desire  to  avoid  more 
general  discussions,  I  recommend  the  omission  of  the 
first  and  last  chapters.  For  me,  however,  the  conception 
of  the  whole  and  the  conception  of  the  parts  are  so 
intimately  related  that  I  should  scarcely  be  able  to  separate 
them. 

PRAGUE,  November  1885 


PREFACE  TO  THE  SECOND  EDITION 

THIS  book  was  intended  to  have  the  effect  of  an 
aper$u,  and,  if  I  may  judge  from  the  occasional 
utterances  of  Avenarius,  H.  Cornelius,  James,  Kiilpe,  Loeb, 
Pearson,  Petzoldt,  Willy,  and  others,  it  seems  to  have 
fulfilled  its  object.  It  now  appears,  after  fourteen  years,  in 
a  new  edition.  This  is  a  rather  bold  undertaking.  For  to 
allow  the  book  to  swell  out  into  a  bulky  volume,  by  adding 
accounts  of  many  experimental  researches  on  points  of 
detail,  and  by  noticing  at  length  the  literature  which  has 
appeared  since  it  was  first  published,  would  not  be  in 
keeping  with  its  character.  Yet  I  was  unwilling  to  let  slip 
this  last  opportunity  without  once  again  saying  something 
on  a  subject  which  I  have  so  much  at  heart.  I  have 
therefore  added  the  supplements  and  elucidations  most 
urgently  required,  principally  by  inserting  short  chapters  in 
the  original  text.  One  of  these,  the  second,  has  already 
appeared  in  the  English  edition  published  in  1897. 


x  THE  ANALYSIS  OF  SENSATIONS 

One  and  the  same  view  underlies  both  my  epistemo- 
logico-physical  writings  and  my  present  attempt  to  deal 
with  the  physiology  of  the  senses — the  view,  namely,  that 
all  metaphysical  elements  are  to  be  eliminated  as  super- 
fluous and  as  destructive  of  the  economy  of  science.  If  I 
have  not  entered  in  these  pages  upon  a  detailed  critical 
and  polemical  discussion  of  views  that  are  opposed  to  my 
own,  this  is  in  truth  not  from  contempt  of  my  opponents, 
but  because  I  am  convinced  that  questions  of  this  kind 
cannot  be  decided  by  controversies  and  dialectic  combats. 
The  only  really  profitable  course  is  to  carry  one's  half- 
thought — or,  it  may  be,  one's  paradoxical  idea — patiently 
about  with  one  for  years,  and  to  make  an  honest  effort  to 
complete  the  half-thought,  or  to  strip  away  the  paradoxical 
element,  as  the  case  may  be.  Those  readers  who,  after 
turning  over  the  first  pages,  lay  the  book  aside,  because 
their  convictions  are  such  that  they  cannot  follow  me  any 
further,  will  only  be  doing  exactly  what  I  myself  have 
sometimes  been  compelled  to  do. 

In  its  former  shape  the  book  met  with  much  friendly 
acceptance,  but  it  also  aroused  strenuous  opposition. 
Readers  who  wish  to  go  more  deeply  into  the  subjects  of 
which  it  treats,  may  find  it  useful  to  know  that  Willy,  in 
a  recently  published  work  (Die  Krisis  in  der  Psychologic, 
Leipzig,  1899),  in  which  a  position  closely  allied  to  my 
own  is  adopted,  opposes  my  views  in  many  points  of 
detail. 

VIENNA,  April  1900 


A  UTHOR'S  PREFA  CES  xi 


PREFACE  TO  THE  THIRD  EDITION 

/""CONTRARY  to  my  expectation,  the  second  edition 
V^/  was  exhausted  in  a  few  months.  I  have  not 
hesitated  to  make  certain  additions  which  may  help  to  put 
my  views  in  a  clearer  light,  though  without  altering  the 
text  of  1886  in  any  essential  respect.  Two  passages  only 
of  the  second  edition  (paragraph  7,  p.  n,  and  paragraph  n, 
p.  15)  have  been  cast  in  a  clearer  form.  Dr.  A.  Lampa, 
lecturer  in  physics  in  this  University,  was  told  by  several 
readers  that  these  passages  were  often  understood  in  a  one- 
sided idealistic  sense,  an  interpretation  which  I  in  no  wise 
intended.  I  am  greatly  obliged  to  Dr.  Lampa  for  giving 
me  this  information.  Chapters  IX.  and  XV.,  in  which 
subjects  touched  upon  in  the  second  edition  are  developed 
at  greater  length,  are  new  additions. 

Unless  all  indications  are  deceptive,  I  no  longer  occupy, 
as  regards  my  views,  anything  like  so  isolated  a  position 
as  I  did  even  a  few  years  ago.  In  addition  to  the  school 
of  Avenarius,  there  are  also  younger  thinkers,  such  as 
H.  Gomperz,  who  are  approaching  my  point  of  view  by 
their  own  paths.  The  differences  that  still  remain  over 
seem  to  me  not  irreconcilable.  But  it  would  be  premature 
to  dispute  about  them  yet.  "  But  the  question  is  one  in 
which  it  is  peculiarly  difficult  to  make  out  precisely  what 
another  man  means,  and  even  what  one  means  oneself." 
The  author  of  this  delightfully  humorous  remark  was 
W.  K.  Clifford,  the  mathematician  ("On  the  Nature  of 
Things-in-themselves,"  Lectures^  vol.  ii.  p.  88),  a  writer  with 


xii  THE  ANALYSIS  OF  SENSATIONS 

an  extremely  close  affinity  to  myself  in  the  direction  of  his 
thought. 

VIENNA,  November  1901 


PREFACE  TO  THE  FOURTH  EDITION 

THE  opinion,  which  is  gradually  coming  to  the  front, 
that  science  ought  to  be  confined  to  the  compendious 
representation  of  the  actual,  necessarily  involves  as  a 
consequence  the  elimination  of  all  superfluous  assumptions 
which  cannot  be  controlled  by  experience,  and,  above  all, 
of  all  assumptions  that  are  metaphysical  in  Kant's  sense. 
If  this  point  of  view  is  kept  firmly  in  mind  in  that  wide  field 
of  investigation  which  includes  the  physical  and  the 
psychical,  we  obtain,  as  our  first  and  most  obvious  step,  the 
conception  of  the  sensations  as  the  common  elements  of 
all  possible'physical  and  psychical  experiences,  which  merely 
consist  in  the  different  kinds  of  ways  in  which  these 
elements  are  combined,  or  in  their  dependence  on  one 
another.  A  whole  series  of  troublesome  pseudo-problems 
at  once  disappears.  The  aim  of  this  book  is  not  to  put 
forward  any  system  of  philosophy,  or  any  comprehensive 
theory  of  the  universe.  It  is  only  the  consequences  of 
this  single  step,  to  which  any  number  of  others  may  be 
attached,  that  are  examined  here.  An  attempt  is  made, 
not  to  solve  all  problems,  but  to  reach  an  epistemological 
position  which  shall  prepare  the  way  for  the  co-operation 
of  special  departments  of  research,  that  are  widely  removed 


A  UTHORS  PREFA  CES  xiii 

from  one  another,  in  the  solution  of  important  problems  of 
detail. 

It  is  from  this  point  of  view  that  the  accounts  of  special 
investigations,  which  are  given  here,  should  be  regarded. 
If  there  is  no  essential  difference  between  the  physical  and 
the  psychical,  we  shall  hope  to  trace  the  same  exact 
connexion,  which  we  seek  in  everything  that  is  physical,  in 
the  relations  between  the  physical  and  the  psychical  also. 
We  then  expect  to  find,  corresponding  to  all  the  details 
which  physiological  analysis  can  discover  in  the  sensa- 
tions, as  many  details  of  physical  nerve-process.  I  have 
tried  to  describe  this  relation,  so  far  as  I  have  been  able 
to  do  so, 

Expressions  of  extravagant  praise  and  of  equally  extra- 
vagant blame,  have  come  to  my  ears.  I  hope  that  what 
I  have  just  said,  by  moderating  both,  may  promote  a  sober 
judgment.  When,  about  thirty-five  years  ago,  I  succeeded, 
by  overcoming  my  own  prejudices,  in  firmly  establishing 
my  present  position  and  in  setting  myself  free  from  the 
greatest  intellectual  discomfort  of  my  life,  I  attained 
thereby  to  a  certain  satisfaction.  At  that  time  I  was  only 
acquainted  with  Kant  and  Herbart.  To-day  I  see  that  a 
whole  host  of  philosophers — positivists,  critical  empiricists, 
adherents  of  the  philosophy  of  immanence,  and  certain 
isolated  scientists  as  well — have  all,  without  any  know- 
ledge of  one  another's  work,  entered  upon  paths  which,  in 
spite  of  all  their  individual  differences,  converge  almost 
towards  one  point.  If,  in  these  circumstances,  I  cannot 
rate  very  high  the  value  of  my  individual  labours,  I  may 
nevertheless  be  permitted  to  believe  that  I  have  not  merely 
pursued  a  subjective  phantom,  but  have  contributed 


xiv  THE  ANALYSIS  OF  SENSATIONS 

towards  the  attainment  of  a  goal  at  which  many  others 
besides  myself  have  been  aiming.  It  would  of  course  be 
absurd,  where  ideas  are  concerned  of  which  the  leading 
threads  reach  back  to  antiquity,  to  set  up  any  claims  to 
priority. 

Dr.  Josef  Pollak  and  Dr.  Wolfgang  Pauli,  lecturers  in  the 
Faculty  of  Medicine  in  the  University  of  Vienna,  have  been 
so  extremely  kind  as  to  read  the  proofs,  for  which  I  thank 
them  most  heartily. 

VIENNA,  November  1902 


CONTENTS 

CHAP.  PAGE 

I.  INTRODUCTORY  REMARKS  :  ANTIMETAPHYSICAL        .          i 
II.  ON  PRECONCEIVED  OPINIONS  .  .  .  .38 

III.  MY  RELATION  TO  RICHARD  AVENARIUS  AND  OTHER 

THINKERS     ......        46 

IV.  THE  CHIEF  POINTS  OF  VIEW  FOR  THE  INVESTIGA- 

TION OF  THE  SENSES          .  .  .  -57 

V.  PHYSICS  AND  BIOLOGY  :  CAUSALITY  AND  TELEOLOGY       83 

VI.  THE  SPACE-SENSATIONS  OF  THE  EYE  .  .  .102 

VII.  FURTHER  INVESTIGATION  OF  SPACE-SENSATIONS       .       122 

VIII.  THE  WILL          ......      171 

IX.  BlOLOGICO  -  TELEOLOGICAL    CONSIDERATIONS   AS   TO 

SPACE  .  .  .  .  .  .181 

X.  THE  RELATIONS  OF  THE  SIGHT-SENSATIONS  TO  ONE 

ANOTHER  AND   TO  OTHER    PSYCHICAL   ELEMENTS         195 

XI.  SENSATION,  MEMORY  AND  ASSOCIATION         .  .  235 

XII.  THE  SENSATION  OF  TIME        ....  245 

XIII.  THE  SENSATIONS  OF  TONE       ....  262 

XIV.  INFLUENCE  OF  THE  PRECEDING  INVESTIGATIONS   ON 

OUR  CONCEPTION  OF  PHYSICS       .  .  .      310 

XV.    HOW   MY   VIEWS   HAVE  BEEN    RECEIVED  .  .         354 

INDEX  OF  SUBJECTS       .....      373 
INDEX  OF  NAMES  .....      377 


I.  INTRODUCTORY    REMARKS: 
ANTIMETAPHYSICAL. 

i. 

THE  great  results  achieved  by  physical  science  in 
modem  times — results  not  restricted  to  its  own 
sphere  but  embracing  that  of  other  sciences  which  em- 
ploy its  help — have  brought  it  about  that  physical  ways 
of  thinking  and  physical  modes  of  procedure  enjoy  on 
all  hands  unwonted  prominence,  and  that  the  greatest 
expectations  are  associated  with  their  application.  In 
keeping  with  this  drift  of  modern  inquiry,  the  physiology  of 
the  senses,  gradually  abandoning  the  method  of  investigat- 
ing sensations  in  themselves  followed  by  men  like  Goethe, 
Schopenhauer,  and  others,  but  with  greatest  success  by 
Johannes  Miiller,  has  also  assumed  an  almost  exclusively 
physical  character.  This  tendency  must  appear  to  us  as 
not  altogether  appropriate,  when  we  reflect  that  physics, 
despite  its  considerable  development,  nevertheless  con- 
stitutes but  a  portion  of  a  larger  collective  body  of  know- 
ledge, and  that  it  is  unable,  with  its  limited  intellectual 
implements,  created  for  limited  and  special  purposes,  to 
exhaust  all  the  subject-matter  in  question.  Without 
renouncing  the  support  of  physics,  it  is  possible  for 
the  physiology  of  the  senses,  not  only  to  pursue  its  own 


2  THE  ANALYSIS  OF  SENSATIONS 

course  of  development,  but  also  to  afford  to  physical  science 
itself  powerful  assistance.  The  following  simple  con- 
siderations will  serve  to  illustrate  this  relation  between 
the  two. 

2. 

Colors,  sounds,  temperatures,  pressures,  spaces,  times, 
and  so  forth,  are  connected  with  one  another  in  manifold 
ways ;  and  with  them  are  associated  dispositions  of  mind, 
feelings,  and  volitions.  Out  of  this  fabric,  that  which  is 
relatively  more  fixed  and  permanent  stands  prominently 
forth,  engraves  itself  on  the  memory,  and  expresses  itself  in 
language.  Relatively  greater  permanency  is  exhibited,  first, 
by  certain  complexes  of  colors,  sounds,  pressures,  and  so 
forth,  functionally  connected  in  time  and  space,  which 
therefore  receive  special  names,  and  are  called  bodies. 
Absolutely  permanent  such  complexes  are  not. 

My  table  is  now  brightly,  now  dimly  lighted.  Its 
temperature  varies.  It  may  receive  an  ink  stain.  One  of 
its  legs  may  be  broken.  It  may  be  repaired,  polished,  and 
replaced  part  by  part.  But,  for  me,  it  remains  the  table  at 
which  I  daily  write. 

My  friend  may  put  on  a  different  coat.  His  countenance 
may  assume  a  serious  or  a  cheerful  expression.  His 
complexion,  under  the  effects  of  light  or  emotion,  may 
change.  His  shape  may  be  altered  by  motion,  or  be 
definitely  changed.  Yet  the  number  of  the  permanent 
features  presented,  compared  with  the  number  of  the 
gradual  alterations,  is  always  so  great,  that  the  latter  may 
be  overlooked.  It  is  the  same  friend  with  whom  I  take  my 
daily  walk. 


THE  ANALYSIS  OF  SENSATIONS  3 

My  coat  may  receive  a  stain,  a  tear.  My  very  manner 
of  expressing  this  shows  that  we  are  concerned  here  with 
a  sum-total  of  permanency,  to  which  the  new  element  is 
added  and  from  which  that  which  is  lacking  is  subsequently 
taken  away. 

Our  greater*  intimacy  with  this  sum-total  of  permanency, 
and  the  preponderance  of  its  importance  for  me  as  con- 
trasted with  the  changeable  element,  impel  us  to  the  partly 
instinctive,  partly  voluntary  and  conscious  economy  of 
mental  presentation  and  designation,  as  expressed  in 
ordinary  thought  and  speech.  That  which  is  presented  in 
a  single  image  receives  a  single  designation,  a  single  name. 

Further,  that  complex  of  memories,  moods,  and  feelings, 
joined  to  a  particular  body  (the  human  body),  which  is 
called  the  "  I "  or  "Ego,"  manifests  itself  as  relatively 
permanent.  I  may  be  engaged  upon  this  or  that  subject, 
I  may  be  quiet  and  cheerful,  excited  and  ill-humored. 
Yet,  pathological  cases  apart,  enough  durable  features 
remain  to  identify  the  ego.  Of  course,  the  ego  also  is  only 
of  relative  permanency. 

The  apparent  permanency  of  the  ego  consists  chiefly 
in  the  single  fact  of  its  continuity,  in  the  slowness  of  its 
changes.  The  many  thoughts  and  plans  of  yesterday  that 
are  continued  to-day,  and  of  which  our  environment  in 
waking  hours  incessantly  reminds  us  (whence  in  dreams  the 
ego  can  be  very  indistinct,  doubled,  or  entirely  wanting), 
and  the  little  habits  that  are  unconsciously  and  involuntarily 
kept  up  for  long  periods  of  time,  constitute  the  groundwork 
of  the  ego.  There  can  hardly  be  greater  differences  in  the 
egos  of  different  people,  than  occur  in  the  course  of  years 
in  one  person.  When  I  recall  to-day  my  early  youth,  I 


4  THE  ANALYSIS  OF  SENSATIONS 

should  take  the  boy  that  I  then  was,  with  the  exception  of 
a  few  individual  features,  for  a  different  person,  were  it  not 
for  the  existence  of  the  chain  of  memories.  Many  an 
article  that  I  myself  penned  twenty  years  ago  impresses 
me  now  as  something  quite  foreign  to  myself.  The  very 
gradual  character  of  the  changes  of  the  body  also  contributes 
to  the  stability  of  the  ego,  but  in  a  much  less  degree  than 
people  imagine.  Such  things  are  much  less  analysed  and 
noticed  than  the  intellectual  and  the  moral  ego.  Personally, 
people  know  themselves  very  poorly.1  When  I  wrote  these 
lines  in  1886,  Ribot's  admirable  little  book,  The  Diseases 
of  Personality  (second  edition,  Paris,  1888,  Chicago,  1895), 
was  unknown  to  me.  Ribot  ascribes  the  principal  r61e  in 
preserving  the  continuity  of  the  ego  to  the  general  sensibility. 
Generally,  I  am  in  perfect  accord  with  his  views.2 

The  ego  is  as  little  absolutely  permanent  as  are  bodies. 
That  which  we  so  much  dread  in  death,  the  annihilation 
of  our  permanency,  actually  occurs  in  life  in  abundant 
measure.  That  which  is  most  valued  by  us,  remains 
preserved  in  countless  copies,  or,  in  cases  of  exceptional 

1  Once,  when  a  young  man,  I  noticed  in  the  street  the  profile  of  a  face 
that  was  very  displeasing  and  repulsive  to  me.     I  was  not  a  little  taken 
aback  when  a  moment  afterwards  I  found  that  it  was  my  own  face  which, 
in  passing  by  a  shop  where  mirrors  were  sold,  I  had  perceived  reflected 
from  two  mirrors  that  were  inclined  at  the  proper  angle  to  each  other. 

Not  long  ago,  after  a  trying  railway  journey  by  night,  when  I  was 
very  tired,  I  got  into  an  omnibus,  just  as  another  man  appeared  at  the 
other  end.  ' '  What  a  shabby  pedagogue  that  is,  that  has  just  entered," 
thought  I.  It  was  myself:  opposite  me  hung  a  large  mirror.  The 
physiognomy  of  my  class,  accordingly,  was  better  known  to  me  than 
my  own. 

2  Cp.   Hume,   Treatise  on  Human  Nature,  Vol.  I.  part  iv.,  p.  6  ; 
Gruithuisen,    Beitragc    zur  Physiognosie  und  Eautognosie,  Munich, 
1812,  pp.  37-58. 


THE  ANALYSIS  OF  SENSATIONS  5 

excellence,  is  even  preserved  of  itself.  In  the  best  human 
being,  however,  there  are  individual  traits,  the  loss  of  which 
neither  he  himself  nor  others  need  regret.  Indeed,  at 
times,  death,  viewed  as  a  liberation  from  individuality,  may 
even  become  a  pleasant  thought.  Such  reflections  of 
course  do  not  make  physiological  death  any  the  easier  to 
bear. 

After  a  first  survey  has  been  obtained,  by  the  formation 
of  the  substance-concepts  "body"  and  "ego"  (matter  and 
soul),  the  will  is  impelled  to  a  more  exact  examination  of 
the  changes  that  take  place  in  these  relatively  permanent 
existences.  The  element  of  change  in  bodies  and  the  ego, 
is  in  fact,  exactly  what  moves  the  will T  to  this  examination. 
Here  the  component  parts  of  the  complex  are  first  exhibited 
as  its  properties.  A  fruit  is  sweet ;  but  it  can  also  be 
bitter.  Also,  other  fruits  may  be  sweet.  The  red  color 
we  are  seeking  is  found  in  many  bodies.  The  neighbor- 
hood of  some  bodies  is  pleasant;  that  of  others, 
unpleasant.  Thus,  gradually,  different  complexes  are 
found  to  be  made  up  of  common  elements.  The  visible, 
the  audible,  the  tangible,  are  separated  from  bodies.  The 
visible  is  analysed  into  colors  and  into  form.  In  the 
manifoldness  of  the  colors,  again,  though  here  fewer  in 
number,  other  component  parts  are  discerned — such  as 
the  primary  colors,  and  so  forth.  The  complexes  are 
disintegrated  into  elements, 2  that  is  to  say,  into  their 
ultimate  component  parts,  which  hitherto  we  have  been 

1  Not  to  be  taken  in  the  metaphysical  sense. 

2  If  this  process  be  regarded  as  an  abstraction,  the  elements,  as  we 
shall  see,  do  not  thereby  lose  anything  of  their  importance.     Cp.  the 
subsequent  discussion  of  concepts  in  Chapter  XIV. 


6  THE  ANALYSIS  OF  SENSATIONS 

unable  to  subdivide  any  further.  The  nature  of  these 
elements  need  not  be  discussed  at  present ;  it  is  possible 
that  future  investigations  may  throw  light  on  it.  We 
need  not  here  be  disturbed  by  the  fact  that  it  is  easier  for 
the  scientist  to  study  relations  of  relations  of  these 
elements  than  the  direct  relations  between  them. 


The  useful  habit  of  designating  such  relatively  permanent 
compounds  by  single  names,  and  of  apprehending  them  by 
single  thoughts,  without  going  to  the  trouble  each  time  of 
an  analysis  of  their  component  parts,  is  apt  to  come  into 
strange  conflict  with  the  tendency  to  isolate  the  component 
parts.  The  vague  image  which  we  have  of  a  given  per- 
manent complex,  being  an  image  which  does  not  perceptibly 
change  when  one  or  another  of  the  component  parts  is  taken 
away,  seems  to  be  something  which  exists  in  itself.  Inas- 
much as  it  is  possible  to  take  away  singly  every  constituent 
part  without  destroying  the  capacity  of  the  image  to  stand 
for  the  totality  and  to  be  recognised  again,  it  is  imagined 
that  it  is  possible  to  subtract  all  the  parts  and  to  have 
something  still  remaining.  Thus  naturally  arises  the  philo- 
sophical notion,  at  first  impressive,  but  subsequently  re- 
cognized as  monstrous,  of  a  "thing-in-itself,"  different  from 
its  "appearance,"  and  unknowable.1 

r   Thing,  body,  matter,  are  nothing  apart  from  the  combi- 
lations  of  the  elements, — the  colors,  sounds,  and  so  forth 

Cp.  W.  Schuppe's  polemic  against  Ueberweg,  printed  in  Brasch's 
Welt-iind  Lebensanschauung  Ueber-wegs,  Leipzig,  1889;  F.J.  Schmidt, 
Das  Aergernis  der  Philosophic:  eine  Kantstudie,  Berlin,  1897. 


THE  ANALYSIS  OF  SENSATIONS  7 

— nothing  apart  from  their  so-called  attributes.  That 
protean  pseudo-philosophical  problem  of  the  single  thing 
with  its  many  attributes,  arises  wholly  from  a  misinter- 
pretation of  the  fact,  that  summary  comprehension  and 
precise  analysis,  although  both  are  provisionally  justifiable 
and  for  many  purposes  profitable,  cannot  be  carried  on 
simultaneously.  A  body  is  one  and  unchangeable  only  so 
long  as  it  is  unnecessary  to  consider  its  details.  Thus 
both  the  earth  and  a  billiard-ball  are  spheres,  if  we  are 
willing  to  neglect  all  deviations  from  the  spherical  form,  and 
if  greater  precision  is  not  necessary.  But  when  we  are 
obliged  to  carry  on  investigations  in  orography  or  micro- 
scopy, both  bodies  cease  to  be  spheres. 


Man  is  pre-eminently  endowed  with  the  power  of  volun- 
tarily and  consciously  determining  his  own  point  of  view. 
He  can  at  one  time  disregard  the  most  salient  features  of 
an  object,  and  immediately  thereafter  give  attention  to  its 
smallest  details  ;  now  consider  a  stationary  current,  without 
a  thought  of  its  contents  (whether  heat,  electricity  or  fluidity), 
and  then  measure  the  width  of  a  Fraunhofer  line  in  the 
spectrum ;  he  can  rise  at  will  to  the  most  general  abstrac- 
tions or  bury  himself  in  the  minutest  particulars.  Animals 
possess  this  capacity  in  a  far  less  degree.  They  do  not 
assume  a  point  of  view,  but  are  usually  forced  to  it  by  their 
sense-impressions.  The  baby  that  does  not  know  its  father 
with  his  hat  on,  the  dog  that  is  perplexed  at  the  new  coat 
of  its  master,  have  both  succumbed  in  this  conflict  of 
points  of  view.  Who  has  not  been  worsted  in  similar 


8  THE  ANALYSIS  OF  SENSATIONS 

plights  ?     Even  the  man  of  philosophy  at  times  succumbs, 
as  the  grotesque  problem,  above  referred  to,  shows. 

In  this  last  case,  the  circumstances  appear  to  furnish 
a  real  ground  of  justification.  Colors,  sounds,  and  the 
odors  of  bodies  are  evanescent.  But  their  tangibility,  as 
a  sort  of  constant  nucleus,  not  readily  susceptible  of 
annihilation,  remains  behind;  appearing  as  the  vehicle 
of  the  more  fugitive  properties  attached  to  it.  Habit, 
thus,  keeps  our  thought  firmly  attached  to  this  central 
nucleus,  even  when  we  have  begun  to  recognize  that  seeing 
hearing,  smelling,  and  touching  are  intimately  akin  in 
character.  A  further  consideration  is,  that  owing  to  the 
singularly  extensive  development  of  mechanical  physics  a 
kind  of  higher  reality  is  ascribed  to  the  spatial  and  to  the 
temporal  than  to  colors,  sounds,  and  odors ;  agreeably  to 
which,  the  temporal  and  spatial  links  of  colors,  sounds, 
and  odors  appear  to  be  more  real  than  the  colors,  sounds 
and  odors  themselves.  The  physiology  of  the  senses, 
however,  demonstrates,  that  spaces  and  times  may  just  as 
appropriately  be  called  sensations  as  colors  and  sounds. 
But  of  this  later. 


Not  only  the  relation  of  bodies  to  the  ego,  but  the  ego 
itself  also,  gives  rise  to  similar  pseudo- problems,  the 
character  of  which  may  be  briefly  indicated  as  follows  : 

Let  us  denote  the  above-mentioned  elements  by  the 
letters  A  B  C  .  .  .,  K  L  M  .  .  '.,  »£/.*.  Let  those 
complexes  of  colors,  sounds,  and  so  forth,  commonly 
called  bodies,  be  denoted,  for  the  sake  of  clearness,  by 


THE  ANALYSIS  OF  SENSATIONS  9 

ABC.  .  . ;  the  complex,  known  as  our  own  body,  which 
is  a  part  of  the  former  complexes  distinguished  by  certain 
peculiarities,  may  be  called  K  L  M  .  .  . ;  the  complex 
composed  of  volitions,  memory-images,  and  the  rest,  we 
shall  represent  by  a  /3  7  ...  Usually,  now,  the  complex 
a  /5  7  .  .  .  K  L  M  .  .  .,  as  making  up  the  ego,  is  opposed 
to  the  complex  ABC.  .  .,  as  making  up  the  world  of 
physical  objects ;  sometimes  also,  a  /3  y  ...  is  viewed  as 
ego,  and-ATZJ/.  .  .ABC.  ..as  world  of  physical' 
objects.  Now,  at  first  blush,  ABC.  .  .  appears  inde- 
pendent of  the  ego,  and  opposed  to  it  as  a  separate  exist- 
ence. But  this  independence  is  only  relative,  and  gives 
way  upon  closer  inspection.  Much,  it  is  true,  may  change 
in  the  complex  a  j8  y  .  .  .  without  much  perceptible  change 
being  induced  in  ABC-.  .  . ;  and  vice  versa.  But  many 
changes  in  a  (3  y  ...  do  pass,  by  way  of  changes  in 
K  L  M  .  .  .,  to  ABC.  .  .;  and  vice  versa.  (As,  for 
example,  when  powerful  ideas  burst  forth  into  acts,  or  when 
our  environment  induces  noticeable  changes  in  our  body.) 
At  the  same  time  the  group  K  L  M .  .  .  appears  to  be  more 
intimately  connected  with  a  /3  y  .  .  .  and  with  ABC.  .  ., 
than  the  latter  with  one  another ;  and  their  relations  find 
their  expression  in  common  thought  and  speech. 

Precisely  viewed,  however,  it  appears  that  the  group 
A  B  C  ...  is  always  codetermined  by  K  L  M.  A  cube 
when  seen  close  at  hand,  looks  large ;  when  seen  at  a 
distance,  small ;  its  appearance  to  the  right  eye  differs  from 
its  appearance  to  the  left ;  sometimes  it  appears  double ; 
with  closed  eyes  it  is  invisible.  The  properties  of  one  and 
the  same  body,  therefore,  appear  modified  by  our  own 
body;  they  appear  conditioned  by  it.  But  where,  now, 


lo          THE  ANALYSIS  OF  SENSATIONS 

••« 

is  that  same  body,  which  appears  so  different?  All  that  can 
be  said  is,  that  with  different  KL  M  different  ABC.  .  . 
are  associated.1 

A  common  and  popular  way  of  thinking  and  speaking 
is  to  contrast  "  appearance "  with  "  reality."  A  pencil 
held  in  front  of  us  in  the  air  is  seen  by  us  as  straight; 
dip  it  into  the  water,  and  we  see  it  crooked.  In  the  latter 
case  we  say  that  the  pencil  appears  crooked,  but  is  in 
reality  straight.  But  what  justifies  us  in  declaring  one 
fact  rather  than  another  to  be  the  reality,  and  degrading 
the  other  to  the  level  of  appearance  ?  In  both  cases  we 
have  to  do  with  facts  which  present  us  with  different  com- 
binations of  the  elements,  combinations  which  in  the  two 
cases  are  differently  conditioned.  Precisely  because  of 
its  environment  the  pencil  dipped  in  water  is  optically 
crooked;  but  it  is  tactually  and  metrically  straight.  An 
image  in  a  concave  or  flat  mirror  is  only  visible,  whereas 
under  other  and  ordinary  circumstances  a  tangible  body 
as  well  corresponds  to  the  visible  image.  A  bright  surface 

1  A  long  time  ago  (in  the  Vierteljahrsschrift  fur  Psychiatric^  Leipzig 
and  Neuwied,  1868,  art.  "  Ueber  die  Abhangigkeit  der  Netzhautstellen 
von  einander")  I  enunciated  this  thought  as  follows  :  The  expression 
"  sense-illusion"  proves  that  we  are  not  yet  fully  conscious,  or  at  least 
have  not  yet  deemed  it  necessary  to  incorporate  the  fact  into  our 
ordinary  language,  that  the  senses  represent  things  neither  "wrongly  nor 
correctly.  All  that  can  be  truly  said  of  the  sense-organs  is,  that,  under 
different  circumstances  they  produce  different  sensations  and  perceptions. 
As  these  "circumstances,"  now,  are  extremely  various  in  character, 
being  partly  external  (inherent  in  the  objects),  partly  internal  (inherent 
in  the  sensory  organs),  and  partly  interior  (having  their  activity  in  the 
central  organs),  it  can  sometimes  appear,  when  we  only  notice  the 
external  circumstances,  as  if  the  organ  acted  differently  under  the 
same  conditions.  And  it  is  customary  to  call  the  unusual  effects, 
deceptions  or  illusions. 


THE  ANALYSIS  OF  SENSATIONS          n 

is  brighter  beside  a  dark  surface  than  beside  one  brighter 
than  itself.  To  be  sure,  our  expectation  is  deceived  when, 
not  paying  sufficient  attention  to  the  conditions,  and  sub- 
stituting for  one  another  different  cases  of  the  combination, 
we  fall  into  the  natural  error  of  expecting  what  we  are 
accustomed  to,  although  the  case  may  be  an  unusual  one. 
The  facts  are  not  to  blame  for  that.  In  these  cases,  to 
speak  of  "appearance"  may  have  a  practical  meaning, 
but  cannot  have  a  scientific  meaning.  Similarly,  the 
question  which  is  often  asked,  whether  the  world  is  real 
or  whether  we  merely  dream  it,  is  devoid  of  all  scientific 
meaning.  Even  the  wildest  dream  is  a  fact  as  much  as 
any  other.  If  our  dreams  were  more  regular,  more  con- 
nected, more  stable,  they  would  also  have  more  practical 
importance  for  us.  In  our  waking  hours  the  relations  of 
the  elements  to  one  another  are  immensely  amplified  in 
comparison  with  what  they  were  in  our  dreams.  We 
recognize  the  dream  for  what  it  is.  When  the  process 
is  reversed,  the  field  of  psychic  vision  is  narrowed;  the 
contrast  is  almost  entirely  lacking.  Where  there  is  no 
contrast,  the  distinction  between  dream  and  waking, 
between  appearance  and  reality,  is  quite  otiose  and 
worthless. 

The  popular  notion  of  an  antithesis  between  appearance 
and  reality  has  exercised  a  very  powerful  influence  on 
scientific  and  philosophical  thought.  We  see  this,  for 
example,  in  Plato's  pregnant  and  poetical  fiction  of  the 
Cave,  in  which,  with  our  backs  turned  towards  the  fire, 
we  observe  merely  the  shadows  of  what  passes  (Reptiblic, 
vii.  i).  But  this  conception  was  not  thought  out  to  its 
final  consequences,  with  the  result  that  it  has  had  an 


12          THE  ANALYSIS  OF  SENSATIONS 

unfortunate  influence  on  our  ideas  about  the  universe. 
The  universe,  of  which  nevertheless  we  are  a  part,  became 
completely  separated  from  us,  and  was  removed  an 
infinite  distance  away.  Similarly,  many  a  young  man, 
hearing  for  the  first  time  of  the  refraction  of  stellar  light, 
has  thought  that  doubt  was  cast  on  the  whole  of  astronomy, 
whereas  nothing  is  required  but  an  easily  effected  and 
unimportant  correction  to  put  everything  right  again. 


6. 

We  see  an  object  having  a  point  S.  If  we  touch  S, 
that  is,  bring  it  into  connexion  with  our  body,  we  receive 
a  prick.  We  can  see  S,  without  feeling  the  prick.  But 
as  soon  as  we  feel  the  prick  we  find  S  on  the  skin.  The 
visible  point,  therefore,  is  a  permanent  nucleus,  to  which 
the  prick  is  annexed,  according  to  circumstances,  as  some- 
thing accidental.  From  the  frequency  of  analogous 
occurrences  we  ultimately  accustom  ourselves  to  regard 
all  properties  of  bodies  as  "effects"  proceeding  from 
permanent  nuclei  and  conveyed  to  the  ego  through  the 
medium  of  the  body;  which  effects  we  call  sensations. 
By  this  operation,  however,  these  nuclei  are  deprived  of 
their  entire  sensory  content,  and  converted  into  mere 
mental  symbols.  The  assertion,  then,  is  correct  that  the 
world  consists  only  of  our  sensations.  In  which  case  we 
have  knowledge  only  of  sensations,  and  the  assumption 
of  the  nuclei  referred  to,  or  of  a  reciprocal  action  between 
them,  from  which  sensations  proceed,  turns  out  to  be  quite 
idle  and  superfluous.  Such  a  view  can  only  suit  with  a  half- 
hearted realism  or  a  half-hearted  philosophical  criticism. 


THE  ANALYSIS  OF  SENSATIONS          13 


Ordinarily  the  complex  a  j3  y  ...  AT  Z  .A/"  ...  is  con- 
trasted as  ego  with  the  complex  ABC...  At  first  only  those 
elements  of  A  B  C  .  .  .  that  more  strongly  alter  a  [3  y  .  .  ., 
as  a  prick,  a  pain,  are  wont  to  be  thought  of  as  comprised 
in  the  ego.  Afterwards,  however,  through  observations 
of  the  kind  just  referred  to,  it  appears  that  the  right  to 
annex  ABC.  .  .  to  the  ego  nowhere  ceases.  In  con- 
formity with  this  view  the  ego  can  be  so  extended  as 
ultimately  to  embrace  the  entire  world.1  The  ego  is  not 
sharply  marked  off,  its  limits  are  very  indefinite  and 
arbitrarily  displaceable.  Only  by  failing  to  observe  this 
fact,  and  by  unconsciously  narrowing  those  limits,  while 
at  the  same  time  we  enlarge  them,  arise,  in  the  conflict 
of  points  of  view,  the  metaphysical  difficulties  met  with 
in  this  connexion. 

As  soon  as  we  have  perceived  that  the  supposed  unities 
"body"  and  "ego"  are  only  makeshifts,  designed  for 
provisional  orientation  and  for  definite  practical  ends  (so 
that  we  may  take  hold  of  bodies,  protect  ourselves  against 
pain,  and  so  forth),  we  find  ourselves  obliged,  in  many 

1  When  I  say  that  the  table,  the  tree,  and  so  forth,  are  my  sensations, 
the  statement,  as  contrasted  with  the  mode  of  representation  of  the 
ordinary  man,  involves  a  real  extension  of  my  ego.  On  the  emotional 
side  also  such  extensions  occur,  as  in  the  case  of  the  virtuoso,  who 
possesses  as  perfect  a  mastery  of  his  instrument  as  he  does  of  his  own 
body;  or  in  the  case  of  the  skilful  orator,  on  whom  the  eyes  of  the 
audience  are  all  converged,  and  who  is  controlling  the  thoughts  of  all ; 
or  in  that  of  the  able  politician  who  is  deftly  guiding  his  party  ;  and  so 
on.  In  conditions  of  depression,  on  the  other  hand,  such  as  nervous  people 
often  endure,  the  ego  contracts  and  shrinks.  A  wall  seems  to  separate 
it  from  the  world. 


14          THE  ANALYSIS  OF  SENSATIONS 

more  advanced  scientific  investigations,  to  abandon  them  as 
insufficient  and  inappropriate.  The  antithesis  between  ego 
and  world,  between  sensation  (appearance)  and  thing,  then 
vanishes,  and  we  have  simply  to  deal  with  the  connexion  of 
the  elements  a$y  .  .  .  A  J?  C .  .  .  KL  M  .  .  .,  of  which 
this  antithesis  was  only  a  partially  appropriate  and  imperfect 
expression.  This  connexion  is  nothing  more  or  less  than 
the  combination  of  the  above-mentioned  elements  with 
other  similar  elements  (time  and  space).  Science  has 
simply  to  accept  this  connexion,  and  to  get  its  bearings  in 
it,  without  at  once  wanting  to  explain  its  existence. 

On  a  superficial  examination  the  complex  a  /3  y  .  .  . 
appears  to  be  made  up  of  much  more  evanescent  elements 
than  ABC...  and  K  L  M  .  .  .,  in  which  last  the 
elements  seem  to  be  connected  with  greater  stability  and  in 
a  more  permanent  manner  (being  joined  to  solid  nuclei  as 
it  were).  Although  on  closer  inspection  the  elements  of 
all  complexes  prove  to  be  homogeneous,  yet  even  when  this 
has  been  recognized,  the  earlier  notion  of  an  antithesis  of 
body  and  spirit  easily  slips  in  again.  The  philosophical 
spiritualist  is  often  sensible  of  the  difficulty  of  imparting  the 
needed  solidity  to  his  mind-created  world  of  bodies ;  the 
materialist  is  at  a  loss  when  required  to  endow  the  world  of 
matter  with  sensation.  The  monistic  point  of  view,  which 
reflexion  has  evolved,  is  easily  clouded  by  our  older  and 
more  powerful  instinctive  notions. 


8. 

The  difficulty  referred  to  is  particularly   felt  when  we 
consider  the  following  case.     In  the  complex  ABC.  .  ., 


THE  ANALYSIS  OF  SENSATIONS          15 

which  we  have  called  the  world  of  matter,  we  find  as  parts, 
not  only  our  own  body  K  L  M .  .  .,  but  also  the  bodies  of 
other  persons  (or  animals)  K'  L'  M'  .  .  .,  K"  L'  M"  .  .  ., 
to  which,  by  analogy,  we  imagine  other  a'  $'  y'  .  .  ., 
a"  (3"  y"  .  .  .,  annexed,  similar  to  a  /3  y  .  .  .  So  long  as 
we  deal  with  Kr  Z'  M' .  .  .,  we  find  ourselves  in  a  thor- 
oughly familiar  province  which  is  at  every  point  accessible^ 
to  our  senses.  When,  however,  we  inquire  after  the  sensa-  \ 
tions  or  feelings  belonging  to  the  body  K'  U  M'  .  .  .,  we 
no  longer  find  these  in  the  province  of  sense  :  we  add  them 
in  thought.  Not  only  is  the  domain  which  we  now  enter 
far  less  familiar  to  us,  but  the  transition  into  it  is  also 
relatively  unsafe.  We  have  the  feeling  as  if  we  were  plung- 
ing into  an  abyss.1  Persons  who  adopt  this  way  of  thinking 
only,  will  never  thoroughly  rid  themselves  of  that  sense  of 
insecurity,  which  is  a  very  fertile  source  of  illusory  problems. 
But  we  are  not  restricted  to  this  course.  Let  us  consider, 
first,  the  reciprocal  relations  of  the  elements  of  the  complex 
ABC.  .  .,  without  regarding  K  L  M  .  .  .  (our  body). 

1  When  I  first  came  to  Vienna  from  the  country,  as  a  boy  of  four  or 
five  years,  and  was  taken  by  my  father  upon  the  walls  of  the  city's 
fortifications,  I  was  very  much  surprised  to  see  people  below  in  the 
moat,  and  could  not  understand  how,  from  my  point  of  view,  they 
could  have  got  there ;  for  the  thought  of  another  way  of  descent  never 
occurred  to  me.  I  remarked  the  same  astonishment,  once  afterwards, 
in  the  case  of  a  three-year-old  boy  of  my  own,  while  walking  on  the  walls 
of  Prague.  I  recall  this  feeling  every  time  I  occupy  myself  with  the 
reflexion  of  the  text,  and  I  frankly  confess  that  this  accidental  experi- 
ence of  mine  helped  to  confirm  my  opinion  upon  this  point,  which  I 
have  now  long  held.  Our  habit  of  always  following  the  same  path, 
whether  materially  or  psychically,  tends  greatly  to  confuse  our  field  of 
survey.  A  child,  on  the  piercing  of  the  wall  of  a  house  in  which  he 
has  long  dwelt,  may  experience  a  veritable  enlargement  of  his  world- 
view,  and  in  the  same  manner  a  slight  scientific  hint  may  often  afford 
great  enlightenment. 


16          THE  ANALYSIS  OF  SENSATIONS 

All  physical  investigations  are  of  this  sort.  A  white  ball 
falls  upon  a  bell ;  a  sound  is  heard.  The  ball  turns  yellow 
before  a  sodium  lamp,  red  before  a  lithium  lamp.  Here 
the  elements  (ABC.  .  .  )  appear  to  be  connected  only 
with  one  another  and  to  be  independent  of  our  body 
(K  L  M  .  .  .  ).  But  if  we  take  santonine,  the  ball  again 
turns  yellow.  If  we  press  one  eye  to  the  side,  we  see  two 
balls.  If  we  close  our  eyes  entirely,  there  is  no  ball  there 
at  all.  If  we  sever  the  auditory  nerve,  no  sound  is  heard. 
The  elements  ABC..  .,  therefore,  are  not  only  con- 
nected with  one  another,  but  also  with  K  L  M.  To  this 
extent,  and  to  this  extent  only>  do  we  call  ABC,., 
sensations^  and  regard  A  B  C  as  belonging  to  the  ego.  In 
what  follows,  wherever  the  reader  finds  the  terms  "  Sensa- 
tion," "  Sensation-complex,"  used  alongside  of  or  instead  of 
the  expressions  "  element,"  "  complex  of  elements,"  it  must 
be  borne  in  mind  that  it  is  only  in  the  connexion  and 
relation  in  question,  only  in  their  functional  dependence, 
that  the  elements  are  sensations.  In  another  functional 
relation  they  are  at  the  same  time  physical  objects.  We 
only  use  the  additional  term  "sensations"  to  describe  the 
elements,  because  most  people  are  much  more  familiar 
with  the  elements  in  question  as  sensations  (colors,  sounds, 
pressures,  spaces,  times,  etc.),  while  according  to  the 
popular  conception  it  is  particles  of  mass  that  are  con- 
sidered as  physical  elements,  to  which  the  elements,  in  the 
sense  here  used,  are  attached  as  "properties  "  or  "effects."  * 

1  A  treatment  of  this  fundamental  point,  identical  in  essentials,  but 
cast  in  a  form  which  will  be  perhaps  more  acceptable  to  scientists,  will 
be  found  in  my  Erkenntnis  und  Irrtum,  Leipzig,  1905  (2nd  edition, 
Leipzig,  1906.) 


THE  ANALYSIS  OF  SENSATIONS          17 

In  this  way,  accordingly,  we  do  not  find  the  gap  between 
bodies  and  sensations  above  described,  between  what  is 
without  and  what  is  within,  between  the  material  world  and 
the  spiritual  world.1  All  elements  A  B  C  .  .  .,  K L  M .  .  ., 
constitute  a  single  coherent  mass  only,  in  which,  when  any 
one  element  is  disturbed,  all  is  put  in  motion ;  except  that 
a  disturbance  in  K  L  M  .  .  .  has  a  more  extensive  and 
profound  action  than  one  in  A  B  C  ...  A  magnet  in  our 
neighborhood  disturbs  the  particles  of  iron  near  it;  a 
falling  boulder  shakes  the  earth  \  but  the  severing  of  a  nerve 
sets  in  motion  the  whole  system  of  elements.-  Quite 
involuntarily  does  this  relation  of  things  suggest  the  picture 
of  a  viscous  mass,  at  certain  places  (as  in  the  ego)  more 
firmly  coherent  than  in  others.  I  have  often  made  use  of 
this  image  in  lectures. 


Thus  the  great  gulf  between  physical  and  psychological 
research  persists  only  when  we  acquiesce  in  our  habitual 
stereotyped  conceptions.  A  color  is  a  physical  object  as 
soon  as  we  consider  its  dependence,  for  instance,  upon  its 
luminous  source,  upon  other  colors,  upon  temperatures, 
upon  spaces,  and  so  forth.  When  we  consider,  however,  its 
dependence  upon  the  retina  (the  elements  KL  M .  .  .), 
it  is  a  psychological  object,  a  sensation.  Not  the  subject- 

1  Compare  my  Grundlinien  der  Lehre  von  den  Bewegungsempfindim- 
gen,  Leipzig,  Engelmann,  1875,  p.  54.  I  there,  for  the  first  time, 
stated  my  view  shortly,  but  definitely,  in  these  words  :  "  Appearance 
may  be  subdivided  into  elements,  which,  in  so  far  as  they  are  connected 
with  certain  processes  of  our  bodies,  and  can  be  regarded  as  conditioned 
by  these  processes,  we  call  sensations." 
B 


i8          THE  ANALYSIS  OF  SENSATIONS 

matter,  but  the  direction  of  our  investigation,  is  different  in 
the  two  domains.     (Cp.  also  Chapter  II.,  pp.  43,  44.) 

Both  in  reasoning  from  the  observation  of  the  bodies 
of  other  men  or  animals,  to  the  sensations  which  they 
possess,  as  well  as  in  investigating  the  influence  of  our 
own  body  upon  our  own  sensations,  we  have  to  complete 
observed  facts  by  analogy.  This  is  accomplished  with 
much  greater  ease  and  certainty,  when  it  relates,  say,  only 
to  nervous  processes,  which  cannot  be  fully  observed  in 
our  own  bodies — that  is,  when  it  is  carried  out  in  the  more 
familiar  ..physical  domain — than  when  it  is  extended  to 
the  psychical  domain,  to  the  sensations  and  thoughts  of 
other  people.  Otherwise  there  is  no  essential  difference. 


10. 

The  considerations  just  advanced,  expressed  as  they  have 
been  in  an  abstract  form,  will  gain  in  strength  and  vividness 
if  we  consider  the  concrete  facts  from  which  they  flow. 
Thus,  I  lie  upon  my  sofa.  .  If  I  close  my  right  eye,  the 
picture  represented  in  the  accompanying  cut  is  presented 
to  my  left  eye.  In  a  frame  formed  by  the  ridge  of  my 
eyebrow,  by  my  nose,  and  by  my  moustache,  appears  a 
part  of  my  body,  so  far  as  visible,  with  its  environment.1 
My  body  differs  from  other  human  bodies — beyond  the 
fact  that  every  intense  motor  idea  is  immediately  ex- 
pressed by  a  movement  of  it,  and  that,  if  it  is  touched, 
more  striking  changes  are  determined  than  if  other  bodies 

1  A  discussion  of  the  binocular  field  of  vision,  with  its  peculiar 
stereoscopic  features,  is  omitted  here,  for  although  familiar  to  all,  it  is 
not  as  easy  to  describe,  and  cannot  be  represented  by  a  single  plane 
drawing. 


THE  ANALYSIS  OF  SENSATIONS          19 

are  touched — by  the   circumstance,  that  it   is   only   seen 
piecemeal,  and,  especially,  is  seen  without  a  head.     If  I 


Fig.  x. 

observe  an  element  A  within  my  field  of  vision,  and 
investigate  its  connexion  with  another  element  B  within 
the  same  field,  I  step  out  of  the  domain  of  physics  into 
that  of  physiology  or  psychology,  provided  B,  to  use  the 


20          THE  ANALYSIS  OF  SENSATIONS 

apposite  expression  of  a  friend  l  of  mine  made  upon  seeing 
this  drawing,  passes  through  my  skin.  Reflexions  like 
that  for  the  field  of  vision  may  be  made  with  regard  to  the 
province  of  touch  and  the  perceptual  domains  of  the  other 
senses.2 

ii. 

Reference  has  already  been  made  to  the  different 
character  of  the  groups  of  elements  denoted  by  A  B  C  .  .  . 
and  a  /3  y  ...  As  a  matter  of  fact,  when  we  see  a  green 
tree  before  us,  or  remember  a  green  tree,  that  is,  represent 
a  green  tree  to  ourselves,  we  are  perfectly  aware  of  the 
difference  of  the  two  cases.  The  represented  tree  has  a 
much  less  determinate,  a  much  more  changeable  form ; 
its  green  is  much  paler  and  more  evanescent ;  and,  what 
is  of  especial  note,  it  plainly  appears  in  a  different  domain. 
A  movement  that  we  will  to  execute  is  never  more  than  a 
represented  movement,  and  appears  in  a  different  domain 
from  that  of  the  executed  movement,  which  always  takes 
place  when  the  image  is  vivid  enough.  Now  the  statement 

1  J.  Popper  of  Vienna. 

2  It  was  about  1870  that  the  idea  of  this  drawing  was  suggested  to 
me  by  an  amusing  chance.     A  certain  Mr  L.,  now  long  dead,  whose 
many  eccentricities  were   redeemed   by  his  truly  amiable  character, 
compelled  me  to  read  one  of  C.  F.   Krause's  writings,  in  which  the 
following  occurs : — 

"  Problem  :  To  carry  out  the  self-inspection  of  the  Ego. 

Solution  :  It  is  carried  out  immediately." 

In  order  to  illustrate  in  a  humorous  manner  this  philosophical  "  much 
ado  about  nothing,"  and  at  the  same  time  to  shew  how  the  self- 
inspection  of  the  Ego  could  be  really  "carried  out,"  I  embarked  on  the 
above  drawing.  Mr  L.'s  society  was  most  instructive  and  stimulating 
to  me,  owing  to  the  naivety  with  which  he  gave  utterance  to  philo- 
sophical notions  that  are  apt  to  be  carefully  passed  over  in  silence  or 
involved  in  obscurity. 


THE  ANALYSIS  OF  SENSATIONS          21 

that  the  elements  A  and  a  appear  in  different  domains, 
means,  if  we  go  to  the  bottom  of  it,  simply  this,  that  these 
elements  are  united  with  different  other  elements.  Thus 
far,  therefore,  the  fundamental  constituents  of  A  B  C  .  .  ., 
a  (3  y  .  .  .  would  seem  to  be  the  same  (colors,  sounds, 
spaces,  times,  motor  sensations  .  .  .),  and  only  the 
character  of  their  connexion  different. 

Ordinarily  pleasure  and  pain  are  regarded  as  different 
from  sensations.  Yet  not  only  tactual  sensations,  but  all 
other  kinds  of  sensations,  may  pass  gradually  into  pleasure 
and  pain.  Pleasure  and  pain  also  may  be  justly  termed 
sensations.  Only  they  are  not  so  well  analysed  and  so 
familiar,  nor,  perhaps,  limited  to  so  few  organs  as  the 
common  sensations.  In  fact,  sensations  of  pleasure  and 
pain,  however  faint  they  may  be,  really  constitute  an 
essential  part  of  the  content  of  all  so-called  emotions. 
Any  additional  element  that  emerges  into  consciousness 
when  we  are  under  the  influence  of  emotions  may  be 
described  as  more  or  less  diffused  and  not  sharply  local- 
ized sensations.  William  James,1  and  after  him  Theodule 
Ribot,2  have  investigated  the  physiological  mechanism  of 
the  emotions  :  they  hold  that  what  is  essential  is  purposive 
tendencies  of  the  body  to  action — tendencies  which  cor- 
respond to  circumstances  and  are  expressed  in  the  organism. 
Only  a  part  of  these  emerges  into  consciousness.  We 
are  sad  because  we  shed  tears,  and  not  vice  versa^ 
says  James.  And  Ribot  justly  observes  that  a  cause  of 
the  backward  state  of  our  knowledge  of  the  emotions  is 

1  W.  James,  Psychology ',  New  York,  1890,  II.,  p.  442. 

2  Th.  Ribot,  La  psychologic  des  sentiments,  1896.     (English  trans- 
lation, The  Psychology  of 'the  Emotions  >  1897.) 


22          THE  ANALYSIS  OF  SENSATIONS 

that  we  have  always  confined  our  observation  to  so  much 
of  these  physiological  processes  as  emerges  into  conscious- 
ness. At  the  same  time  he  goes  too  far  when  he  main- 
tains that  everything  psychical  is  merely  " surajoute"  to 
the  physical,  and  that  it  is  only  the  physical  that  produces 
effects.  For  us  this  distinction  is  non-existent. 

Thus,  perceptions,  presentations,  volitions,  and  emotions, 
in  short  the  whole  inner  and  outer  world,  are  put  together,  in 
combinations  of  varying  evanescence  and  permanence,  out 
of  a  small  number  of  homogeneous  elements.  Usually,  these 
elements  are  called  sensations.  But  as  vestiges  of  a  one- 
sided theory  inhere  in  that  term,  we  prefer  to  speak  simply  of 
elements,  as  we  have  already  done.  The  aim  of  all  research 
is  to  ascertain  the  mode  of  connexion  of  these  elements.1 
If  it  proves  impossible  to  solve  the  problem  by  assuming  one 
set  of  such  elements,  then  more  than  one  will  have  to  be 
assumed.  But  for  the  questions  under  discussion  it  would  be 
improper  to  begin  by  making  complicated  assumptions  in 
advarice. 

12. 

That  in  this  complex  of  elements,  which  fundamentally 
is  only  one,  the  boundaries  of  bodies  and  of  the  ego  do 
not  admit  of  being  established  in  a  manner  definite  and 
sufficient  for  all  cases,  has  already  been  remarked.  To 
bring  together  elements  that  are  most  intimately  connected 
with  pleasure  and  pain  into  one  ideal  mental-economical 

1  Compare  the  note  at  the  conclusion  of  my  treatise,  Die  Geschichte 
^lnd  die  Wurzel  des  Satzes  der  Erhaltung  der  Arbeit,  Prague,  Calve, 
1 872.  {History  and  Root  of  the  Principle,  of  the  Conservation  of  Energy. 
Translated  and  annotated  by  P.  E.  B.  Jourdain,  Chicago,  Open  Court 
Publishing  Co.,  1911.) 


THE  ANALYSIS  OF  SENSATIONS          23 

unity,  the  ego ;  this  is  a  task  of  the  highest  importance 
for  the  intellect  working  in  the  service  of  the  pain-avoiding, 
pleasure-seeking  will.  The  delimitation  of  the  ego,  there- 
fore, is  instinctively  effected,  is  rendered  familiar,  and 
possibly  becomes  fixed  through  heredity.  Owing  to  their 
high  practical  importance,  not  only  for  the  individual,  but 
for  the  entire  species,  the  composites  "  ego  "  and  "  body  " 
instinctively  make  good  their  claims,  and  assert  themselves 
with  elementary  force.  In  special  cases,  however,  in  which 
practical  ends  are  not  concerned,  but  where  knowledge 
is  an  end  in  itself,  the  delimitation  in  question  may  prove 
to  be  insufficient,  obstructive,  and  untenable.1 

The  primary  fact  is  not  the  ego,  but  the  elements 
(sensations).  What  was  said  on  p.  21  as  to  the  term 
"  sensation "  must  be  borne  in  mind.  The  elements 
constitute  the  I.  7  have  the  sensation  green,  signifies 
that  the  element  green  occurs  in  a  given  complex  of  other 
elements  (sensations,  memories).  When  7  cease  to  have 
the  sensation  green,  when  7  die,  then  the  elements  no 

1  Similarly,  class-consciousness,  class-prejudice,  the  feeling  of  nation- 
ality, and  even  the  narrowest-minded  local  patriotism  may  have  a  high 
importance,  jor  certain  purposes.  But  such  attitudes  will  not  be 
shared  by  the  broad-minded  investigator,  at  least  not  in  moments  of 
research.  All  such  egoistic  views  are  adequate  only  for  practical 
purposes.  Of  course,  even  the  investigator  may  succumb  to  habit. 
Trifling  pedantries  and  nonsensical  discussions  ;  the  cunning  appro- 
priation of  others'  thoughts,  with  perfidious  silence  as  to  the  sources  ; 
when  the  word  of  recognition  must  be  given,  the  difficulty  of  swallow- 
ing one's  defeat,  and  the  too  common  eagerness  at  the  same  time  to  set 
the  opponent's  achievement  in  a  false  light :  all  this  abundantly  shows 
that  the  scientist  and  scholar  have  also  the  battle  of  existence  to  fight, 
that  the  ways  even  of  science  still  lead  to  the  mouth,  and  that  the 
pure  impulse  towards  knowledge  is  still  an  ideal  in  our  present  social 
conditions. 


24          THE  ANALYSIS  OF  SENSATIONS 

longer  occur  in  the  ordinary,  familiar  association.  That 
is  all.  Only  an  ideal  mental-economical  unity,  not  a  real 
unity,  has  ceased  to  exist.  The  ego  is  not  a  definite, 
unalterable,  sharply  -  bounded  unity.  None  of  these 
attributes  are  important ;  for  all  vary  even  within  the 
sphere  of  individual  life;  in  fact  their  alteration  is  even 
sought  after  by  the  individual.  Continuity  alone  is 
important.  This  view  accords  admirably  with  the  position 
which  Weismann  has  reached  by  biological  investigations. 
("  Zur  Frage  der  Unsterblichkeit  der  Einzelligen,"  Biolog. 
Centralbl.^  Vol.  IV.,  Nos.  21,  22 ;  compare  especially 
pages  654  and  655,  where  the  scission  of  the  individual 
into  two  equal  halves  is  spoken  of.)  But  continuity  is 
only  a  means  of  preparing  and  conserving  what  is  con- 
tained in  the  ego.  This  content,  and  not  the  ego,  is  the 
principal  thing.  This  content,  however,  is  not  confined 
to  the  individual.  With  the  exception  of  some  insignificant 
and  valueless  personal  memories,  it  remains  preserved  in 
others  even  after  the  death  of  the  individual.  The  elements 
that  make  up  the  consciousness  of  a  given  individual  are 
firmly  connected  with  one  another,  but  with  those  of 
another  individual  they  are  only  feebly  connected,  and 
the  connexion  is  only  casually  apparent.  Contents  of 
consciousness,  however,  that  are  of  universal  significance, 
break  through  these  limits  of  the  individual,  and,  attached 
of  course  to  individuals  again,  can  enjoy  a  continued  exist- 
ence of  an  impersonal,  superpersonal  kind,  independently 
of  the  personality  by  means  of  which  they  were  developed. 
To  contribute  to  this  is  the  greatest  happiness  of  the  artist, 
the  scientist,  the  inventor,  the  social  reformer,  etc. 

The  ego  must  be  given  up.     It  is  partly  the  perception 


THE  ANALYSIS  OF  SENSATIONS          25 

of  this  fact,  partly  the  fear  of  it,  that  has  given  rise  to  the 
many  extravagances  of  pessimism  and  optimism,  and  to 
numerous  religious,  ascetic,  and  philosophical  absurdities. 
In  the  long  run  we  shall  not  be  able  to  close  our  eyes  to 
this  simple  truth,  which  is  the  immediate  outcome  of 
psychological  analysis.  We  shall  then  no  longer  place  so 
high  a  value  upon  the  ego,  which  even  during  the  in- 
dividual life  greatly  changes,  and  which,  in  sleep  or  during 
absorption  in  some  idea,  just  in  our  very  happiest 
moments,  may  be  partially  or  wholly  absent.  We  shall 
then  be  willing  to  renounce  individual  immortality,1  and 
not  place  more  value  upon  the  subsidiary  elements  than 
upon  the  principal  ones.  In  this  way  we  shall  arrive  at 
a  freer  and  more  enlightened  view  of  life,  which  will 
preclude  the  disregard  of  other  egos  and  the  over- 
estimation  of  our  own.  The  ethical  ideal  founded  on 
this  view  of  life  will  be  equally  far  removed  from  the 
ideal  of  the  ascetic,  which  is  not  biologically  tenable  for 
whoever  practises  it,  and  vanishes  at  once  with  his  dis- 
appearance, and  from  the  ideal  of  an  overweening 
Nietzschean  "superman,"  who  cannot,  and  I  hope  will 
not  be  tolerated  by  his  fellow-men.2 

If  a  knowledge  of  the  connexion  of  the  elements  (sensa- 
tions) does  not  suffice  us,  and  we  ask,  Who  possesses  this 
connexion  of  sensations,  Who  experiences  it?  then  we 
have  succumbed  to  the  old  habit  of  subsuming  every 

1  In  wishing  to  preserve  our  personal  memories  beyond  death,  we 
are  behaving  like  the  astute  Eskimo,  who  refused  with  thanks  the  gift 
of  immortality  without  his  seals  and  walruses. 

2  However  far   the   distance  is  from   theoretical   understanding   to 
practical  conduct,  still  the  latter  cannot   in   the  long  run  resist  the 
former. 


26          THE  ANALYSIS  OF  SENSATIONS 

element  (every  sensation)  under  some  unanalysed  complex, 
and  we  are  falling  back  imperceptibly  upon  an  older, 
lower,  and  more  limited  point  of  view.  It  is  often  pointed 
out,  that  a  psychical  experience  which  is  not  the  experience 
of  a  determinate  subject  is  unthinkable,  and  it  is  held  that 
in  this  way  the  essential  part  played  by  the  unity  of  con- 
sciousness has  been  demonstrated.  But  the  Ego-conscious- 
ness can  be  of  many  different  degrees  and  composed  of  a 
multiplicity  of  chance  memories.  One  might  just  as  well 
say  that  a  physical  process  which  does  not  take  place  in 
some  environment  or  other,  or  at  least  somewhere  in  the 
universe,  is  unthinkable.  In  both  cases,  in  order  to  make 
a  beginning  with  our  investigation,  we  must  be  allowed  to 
abstract  from  the  environment,  which,  as  regards  its  influ- 
ence, may  be  very  different  in  different  cases,  and  in  special 
cases  may  shrink  to  a  minimum.  Consider  the  sensations 
of  the  lower  animals,  to  which  a  subject  with  definite 
features  can  hardly  be  ascribed.  It  is  out  of  sensations 
that  the  subject  is  built  up,  and,  once  built  up,  no  doubt 
the  subject  reacts  in  turn  on  the  sensations. 

The  habit  of  treating  the  unanalysed  ego  complex  as  an 
indiscernible  unity  frequently  assumes  in  science  remark- 
able forms.  First,  the  nervous  system  is  separated  from 
the  body  as  the  seat  of  the  sensations.  In  the  nervous 
system  again,  the  brain  is  selected  as  the  organ  best  fitted 
for  this  end,  and  finally,  to  save  the  supposed  psychical 
unity,  a  point  is  sought  in  the  brain  as  the  seat  of  the  soul. 
But  such  crude  conceptions  are  hardly  fit  even  to  fore- 
shadow the  roughest  outlines  of  what  future  research  will 
do  for  the  connexion  of  the  physical  and  the  psychical. 
The  fact  that  the  different  organs  and  parts  of  the  nervous 


THE  ANALYSIS  OF  SENSATIONS          27 

system  are  physically  connected  with,  and  can  be  readily 
excited  by,  one  another,  is  probably  at  the  bottom  of  the 
notion  of  "  psychical  unity." 

I  once  heard  the  question  seriously  discussed,  "How 
the  perception  of  a  large  tree  could  find  room  in  the  little 
head  of  a  man?"  Now,  although  this  "problem"  is  no 
problem,  yet  it  renders  us  vividly  sensible  of  the  absurdity 
that  can  be  committed  by  thinking  sensations  spatially  into 
the  brain.  When  I  speak  of  the  sensations  of  another 
person,  those  sensations  are,  of  course,  not  exhibited  in 
my  optical  or  physical  space ;  they  are  mentally  added,  and 
I  conceive  them  causally,  not  spatially,  attached  to  the 
brain  observed,  or  rather,  functionally  presented.  When  I 
speak  of  my  own  sensations,  these  sensations  do  not  exist 
spatially  in  my  head,  but  rather  my  "head"  shares  with 
them  the  same  spatial  field,  as  was  explained  above. 
(Compare  the  remarks  on  Fig.  i  on  pp.  17-19  above.)1 

The  unity  of  consciousness  is  not  an  argument  in  point. 

1  As  early  as  the  writings  of  Johannes  Miiller,  we  can  already  find  a 
tendency  towards  views  of  this  kind,  although  his  metaphysical  bias 
prevents  him  from  carrying  them  to  their  logical  conclusion.  But 
Hering  (Hermann's  Handb^tch  der  Physiologic,  Vol.  III.,  p.  345)  has 
the  following  characteristic  passage:  "The  material  of  which  visual 
objects  consists  is  the  visual  sensations.  The  setting  sun,  as  a  visual 
object,  is  a  flat,  circular  disk,  which  consists  of  yellowish-red  color, 
that  is  to  say  of  a  visual  sensation.  We  may  therefore  describe  it 
directly  as  a  circular,  yellowish-red  sensation.  This  sensation  we  have 
in  the  very  place  where  the  sun  appears  to  us."  I  must  confess  that,  so 
far  as  the  experiments  go  which  I  have  had  occasion  to  make  in  con- 
versation, most  people,  who  have  not  come  to  close  quarters  with 
these  questions  by  serious  thinking,  will  pronounce  this  way  of  looking 
at  the  matter  to  be  mere  hair-splitting.  Of  course,  what  is  chiefly 
responsible  for  their  indignation  is  the  common  confusion  between 
sensible  and  conceptual  space.  But  anyone  who  takes  his  stand  as  I 
do  on  the  economic  function  of  science,  according  to  which  nothing  is 


28          THE  ANALYSIS  OF  SENSATIONS 

Since  the  apparent  antithesis  between  the  real  world  and 
the  world  given  through  the  senses  lies  entirely  in  our 
mode  of  view,  and  no  actual  gulf  exists  between  them,  a 
complicated  and  variously  interconnected  content  of  con- 
sciousness is  no  more  difficult  to  understand  than  is  the 
complicated  interconnexion  of  the  world. 

If  we  regard  the  ego  as  a  real  unity,  we  become  involved 
in  the  following  dilemma :  either  we  must  set  over  against 
the  ego  a  world  of  unknowable  entities  (which  would  be 
quite  idle  and  purposeless),  or  we  must  regard  the  whole 
world,  the  egos  of  other  people  included,  as  comprised  in 
our  own  ego  (a  proposition  to  which  it  is  difficult  to  yield 
serious  assent). 

But  if  we  take  the  ego  simply  as  a  practical  unity,  put 
together  for  purposes  of  provisional  survey,  or  as  a  more 
strongly^cohering  group  of  elements,  less  strongly  connected 
with  other  groups  of  this  kind,  questions  like  those  above 
discussed  will  not  arise,  and  research  will  have  an  unob- 
structed future. 

In  his  philosophical  notes  Lichtenberg  says :  "  We 
important  except  what  can  be  observed  or  is  a  datum  for  us,  and 
everything  hypothetical,  metaphysical  and  superfluous,  is  to  be 
eliminated,  must  reach  the  same  conclusion.  I  think  that  a  similar 
standpoint  is  to  be  ascribed  to  Avenarius,  for  in  his  Der  menschliche 
Weltbegriff,  p.  76,  the  following  passages  occur:  "The  brain  is  not 
the  dwelling-place,  seat  or  producer  of  thought ;  it  is  not  the  instru- 
ment or  organ,  it  is  not  the  vehicle  or  substratum,  etc.,  of  thought." 
"Thought  is  not  an  indweller  or  command-giver,  it  is  not  a  second 
half  or  aspect,  etc.,  nor  is  it  a  product;  it  is  not  even  a  physiological 
function  of  the  brain,  nor  is  it  a  state  of  the  brain  at  all. "  I  am  not 
able  or  willing  to  subscribe  to  all  that  Avenarius  says  or  to  any  inter- 
pretation of  what  he  says,  but  still  his  conception  seems  to  me  to 
approximate  very  nearly  to  my  own.  The  method  which  he  terms, 
"The  exclusion  of  introjection,"  is  only  a  particular  form  of  the 
elimination  of  the  metaphysical. 


THE  ANALYSIS  OF  SENSATIONS          29 

become  conscious  of  certain  presentations  that  are  not 
dependent  upon  us  ;  of  others  that  we  at  least  think 
are  dependent  upon  us.  Where  is  the  border-line?  We 
know  only  the  existence  of  our  sensations,  presentations, 
and  thoughts.  We  should  say,  //  thinks,  just  as  we 
say,  //  lightens.  It  is  going  too  far  to  say  cogito,  if  we 
translate  cogito  by  /  think.  The  assumption,  or  postula- 
tion,  of  the  ego  is  a  mere  practical  necessity."  Though  the 
method  by  which  Lichtenberg  arrived  at  this  result  is  some- 
what different  from  ours,  we  must  nevertheless  give  our  full 
assent  to  his  conclusion. 


Bodies  do  not  produce  sensations,  but  complexes 
of  elements  (complexes  of  sensations)  make  up  bodies. 
If,  to  the  physicist,  bodies  appear  the  real,  abiding 
existences,  whilst  the  "  elements  "  are  regarded  merely  as 
their  evanescent,  transitory  appearance,  the  physicist  for- 
gets, in  the  assumption  cf  such  a  view,  that  all  bodies  are 
but  thought-symbols  for  complexes  of  elements  (complexes 
of  sensations).  Here,  too,  the  elements  in  question  form 
the  real,  immediate,  and  ultimate  foundation,  which  it  is 
the  task  of  physiologico-physical  research  to  investigate. 
By  the  recognition  of  this  fact,  many  points  of  physiology 
and  physics  assume  more  distinct  and  more  economical 
forms,  and  many  spurious  problems  are  disposed  of. 

For  us,  therefore,  the  world  does  not  consist  of 
mysterious  entities,  which  by  their  interaction  with 
another,  equally  mysterious  entity,  the  ego,  produce 
sensations,  which  alone  are  accessible.  For  us,  colors, 
sounds,  spaces,  times,  .  .  .  are  provisionally  the  ultimate 


3o          THE  ANALYSIS  OF  SENSATIONS 

elements,  whose   given   connexion   it   is   our   business   to 
investigate.1     It  is  precisely  in  this  that  the  exploration  of 

1  I  have  always  felt  it  as  a  stroke  of  special  good  fortune,  that  early  in 
life,  at  about  the  age  of  fifteen,  I  lighted,  in  the  library  of  my  father,  on 
a  copy  of  Kant's  Prolegomena  to  any  Future  Metaphysics.  The  book 
made  at  the  time  a  powerful  and  ineffaceable  impression  upon  me,  the 
like  of  which  I  never  afterwards  experienced  in  any  of  my  philosophical 
reading.  Some  two  or  three  years  later  the  superfluity  of  the  r61e 
played  by  "the  thing  in  itself"  abruptly  dawned  upon  me.  On  a 
bright  summer  day  in  the  open  air,  the  world  with  my  ego  suddenly 
appeared  to  me  as  one  coherent  mass  of  sensations,  only  more  strongly 
coherent  in  the  ego.  Although  the  actual  working  out  of  this  thought 
did  not  occur  until  a  later  period,  yet  this  moment  was  decisive  for  my 
whole  view.  I  had  still  to  struggle  long  and  hard  before  I  was  able  to 
retain  the  new  conception  in  my  special  subject.  With  the  valuable 
parts  of  physical  theories  we  necessarily  absorb  a  good  dose  of  false 
metaphysics,  which  it  is  very  difficult  to  sift  out  from  what  deserves  to 
be  preserved,  especially  when  those  theories  have  become  very  familiar 
to  us.  At  times,  too,  the  traditional,  instinctive  views  would  arise 
with  great  power  and  place  impediments  in  my  way.  Only  by  alternate 
studies  in  physics  and  in  the  physiology  of  the  senses,  and  by  historico- 
physical  investigations  (since  about  1863),  and  after  having  endeavored 
in  vain  to  settle  the  conflict  by  a  physico-psychological  monadology 
(in  my  lectures  on  psycho-physics,  in  the  Zeitschrift  fiir  praktische 
Heilkunde,  Vienna,  1863,  p.  364),  have  I  attained  to  any  considerable 
stability  in  my  views.  I  make  no  pretensions  to  the  title  of  philosopher. 
I  only  seek  to  adopt  in  physics  a  point  of  view  that  need  not  be  changed 
the  moment  our  glance  is  carried  over  into  the  domain  of  another 
science ;  for,  ultimately,  all  must  form  one  whole.  The  molecular 
physics  of  to-day  certainly  does  not  meet  this  requirement.  What  I 
say  I  have  probably  not  been  the  first  to  say.  I  also  do  not  wish  to 
offer  this  exposition  of  mine  as  a  special  achievement.  It  is  rather  my 
belief  that  every  one  will  be  led  to  a  similar  view,  who  makes  a 
careful  survey  of  any  extensive  body  of  knowledge.  Avenarius,  with 
whose  works  I  became  acquainted  in  1883,  approaches  my  point  of  view 
(Philosophic  als  Denken  der  Welt  nach  dem  Princip  des  kleinsten  Kraft- 
masses^  1876).  Also  Hering,  in  his  paper  on  Memory  {Almanack  der 
Wiener  Akademie,  1870,  p.  258  ;  English  translation,  O.  C.  Pub.  Co., 
Chicago,  4th  edition,  enlarged,  1913),  and  J.  Popper  in  his  beautiful 
book,  Das  Rchte  zu  leben  und  die  Pflicht  zu  sterben  (Leipzig,  1878,  p. 
62),  have  advanced  allied  thoughts.  Compare  also  my  paper  Ueber 


THE  ANALYSIS  OF  SENSATIONS  31 

reality  consists.  In  this  investigation  we  must  not  allow 
ourselves  to  be  impeded  by  such  abridgments  and 
delimitations  as  body,  ego,  matter,  spirit,  etc.,  which  have 
been  formed  for  special,  practical  purposes  and  with 
wholly  provisional  and  limited  ends  in  view.  On  the 
contrary,  the  fittest  forms  of  thought  must  be  created  in  and 
by  that  research  itself,  just  as  is  done  in  every  special  science. 
In  place  of  the  traditional,  instinctive  ways  oif,4<hought,  a 
freer,  fresher  view,  conforming  to  developed  experience,  and 
reaching  out  beyond  the  requirements  of  practical  life,  must 
be  substituted  throughout. 

14. 

Science  always  has  its  origin  in  the  adaptation  of  thought  to 
some  definite  field  of  experience.  The  results  of  the  adapta- 
tion are  thought-elements,  which  are  able  to  represent  the 
whole  field.  The  outcome,  of  course,  is  different,  according 
to  the  character  and  extent  of  the  field.  If  the  field  of 
experience  is  enlarged,  or  if  several  fields  heretofore  discon- 
nected are  united,  the  traditional,  familiar  thought-elements 
no  longer  suffice  for  the  extended  field.  In  the  struggle  of 
acquired  habit  with  the  effort  after  adaptation,  problems 
arise,  which  disappear  when  the  adaptation  is  perfected,  to 
make  room  for  others  which  have  arisen  meanwhile. 

die  okonomische  Natur  der  physikalischen  Forschung  {Almanack  der 
Wiener  A kademie,  1882,  p.  179,  note ;  English  translation  in  my  Popular 
Scientific  Lectures,  Chicago,  1894).  Finally  let  me  also  refer  here  to 
the  introduction  to  W.  Preyer's  Reine  Empfindungshhre,  to  Riehl's 
Freiburger  Antrittsrede,  p.  40,  and  to  R.  Wahle's  Gehirn  und 
Bewusstsein,  1884.  My  views  were  indicated  briefly  in  1872  and  1875, 
and  not  expounded  at  length  until  1882  and  1883.  I  should  probably 
have  much  additional  matter  to  cite  as  more  or  less  allied  to  this  line 
of  thought,  if  my  knowledge  of  the  literature  were  more  extensive. 


32  THE  ANALYSIS  OF  SENSATIONS 

To  the  physicist,  qua  physicist,  the  idea  of  "body"  is 
productive  of  a  real  facilitation  of  view,  and  is  not  the 
cause  of  disturbance.  So,  also,  the  person  with  purely 
practical  aims,  is  materially  supported  by  the  idea  of  the 
/  or  ego.  For,  unquestionably,  every  form  of  thought  that 
has  been  designedly  or  undesignedly  constructed  for  a 
given  purpose,  possesses  for  that  purpose  a  permanent 
value.  When,  however,  physics  and  psychology  meet,  the 
ideas  held  in  the  one  domain  prove  to  be  untenable  in  the 
other.  From  the  attempt  at  mutual  adaptation  arise  the 
various  atomic  and  monadistic  theories — which,  however, 
never  attain  their  end.  If  we  regard  sensations,  in  the 
sense  above  defined  (p.  13),  as  the  elements  of  the  world, 
the  problems  referred  to  appear  to  be  disposed  of  in  all 
essentials,  and  the  first  and  most  important  adaptation  to 
be  consequently  effected.  This  fundamental  view  (without 
any  pretension  to  being  a  philosophy  for  all  eternity)  can 
at  present  be  adhered  to  in  all  fields  of  experience ;  it  is 
consequently  the  one  that  accommodates  itself  with  the 
least  expenditure  of  energy,  that  is,  more  economically 
than  any  other,  to  the  present  temporary  collective  state 
of  knowledge  Furthermore,  in  the  consciousness  of  its 
purely  economical  function,  this  fundamental  view  is 
eminently  tolerant.  It  does  not  obtrude  itself  into  fields 
in  which  the  current  conceptions  are  still  adequate.  It 
is  also  ever  ready,  upon  subsequent  extensions  of  the 
field  of  experience,  to  give  way  before  a  better  con- 
ception. 

The  presentations  and  conceptions  of  the  average  man 
of  the  world  are  formed  and  dominated,  not  by  the  full 
and  pure  desire  for  knowledge  as  an  end  in  itself,  but  by 


THE  ANALYSIS  OF  SENSATIONS          33 

the  struggle  to  adapt  himself  favourably  to  the  conditions 
of  life.     Consequently  they  are  less  exact,  but  at  the  same 
time  also  they  are  preserved  from  the  monstrosities  which 
easily  result   from   a   one-sided   and   impassioned   pursuit 
of  a  scientific  or  philosophical  point  of  view.     The  unpre- 
judiced man  of  normal  psychological  development  takes  the 
elements  which  we  have  called  A  B  C  .  .  .  to  be  spatially 
contiguous  and   external   to   the   elements  K  L  M  .  .  ., 
and  he  holds  this  view  immediately ',  and  not  by  any  process 
of  psychological  projection  or  logical  inference  or  construc- 
tion;  even  were  such  a  process  to  exist,  he  would  certainly 
not   be   conscious   of  it.      He   sees,    then,   an  "external 
world  "ABC...  different  from  his  body  K  L  M  .  .  . 
and  existing  outside  it.     As  he  does  not  observe  at  first 
the  dependence  of  the  A  B  Cs  .  .  .  on  the  K  L  M's  .  .  . 
(which  are  always  repeating  themselves  in  the  same  way 
and  consequently  receive  little  attention),  but   is   always 
dwelling  upon  the  fixed  connexion  of  the  A  B  Cs  .  .  . 
with  one  another,  there  appears  to  him  a  world  of  things 
independent   of  his   Ego.     This    Ego   is   formed   by   the 
observation  of  the  special  properties  of  the  particular  thing 
K  L  M  .  .  .  with  which  pain,  pleasure,  feeling,  will,  etc., 
are    intimately    connected.      Further,    he    notices    things 
K'  L'  M',  K"  L"  M",  which  behave  in  a  manner  perfectly 
analogous  to  K  L  M,  and  whose  behaviour  he  thoroughly 
understands  as  soon  as  he  has  thought  of  analogous  feel- 
ings, sensations,  etc.,  as  attached  to  them  in  the  same  way 
as   he    observed    these    feelings,    sensations,    etc.,   to   be 
attached  to  himself.     The  analogy  impelling  him  to  this 
result  is    the    same   as    determines   him,   when    he    has 
observed   that   a   wire   possesses  all  the  properties  of  a 


34          THE  ANALYSIS  OF  SENSATIONS 

conductor  charged  with  an  electric  current,  except  one 
which  has  not  yet  been  directly  demonstrated,  to  conclude 
that  the  wire  possesses  this  one  property  as  well.  Thus, 
since  he  does  not  perceive  the  sensations  of  his  fellow- 
men  or  of  animals  but  only  supplies  them  by  analogy, 
while  he  infers  from  the  behaviour  of  his  fellow-men  that 
they  are  in  the  same  position  over  against  himself,  he  is 
led  to  ascribe  to  the  sensations,  memories,  etc.,  a  particular 
ABC...KLM...viz.  different  nature,  always 
differently  conceived  according  to  the  degree  of  civilization 
he  has  reached ;  but  this  process,  as  was  shown  above,  is  un- 
necessary, and  in  science  leads  into  a  maze  of  error,  although 
the  falsification  is  of  small  significance  for  practical  life. 

These  factors,  determining  as  they  do  the  intellectual 
outlook  of  the  plain  man,  make  their  appearance  alter- 
nately in  him  according  to  the  requirements  of  practical 
life  for  the  time  being,  and  persist  in  a  state  of  nearly 
stable  equilibrium.  The  scientific  conception  of  the  world, 
however,  puts  the  emphasis  now  upon  one,  now  upon  the 
other  factor,  makes  sometimes  one  and  sometimes  the 
other  its  starting-point,  and,  in  its  struggle  for  greater  pre- 
cision, unity  and  consistency,  tries,  so  far  as  seems  possible, 
to  thrust  into  the  background  all  but  the  most  indispensable 
conceptions.  In  this  way  dualistic  and  monistic  systems  arise. 

The  plain  man  is  familiar  with  blindness  and  deafness, 
and  knows  from  his  everyday  experience  that  the  look  of 
things  is  influenced  by  his  senses ;  but  it  never  occurs  to 
him  to  regard  the  whole  world  as  the  creation  of  his  senses. 
He  would  find  an  idealistic  system,  or  such  a  monstrosity  as 
solipsism,  intolerable  in  practice. 

It  may  easily  become  a  disturbing  element  in  unpre- 


THE  ANALYSIS  OF  SENSATIONS 


35 


judiced  scientific  theorizing  when  a  conception  which  is 
adapted  to  a  particular  and  strictly  limited  purpose  is 
promoted  in  advance  to  be  the  foundation  of  all  investiga- 
tion. This  happens,  for  example,  when  all  experiences  are 
regarded  as  "  effects  "  of  an  external  world  extending  into 
consciousness.  This  conception  gives  us  a  tangle  of  meta- 
physical difficulties  which  it  seems  impossible  to  unravel. 
But  the  spectre  vanishes  at  once  when  we  look  at  the 
matter  as  it  were  in  a  mathematical  light,  and  make  it  clear 
to  ourselves  that  all  that  is  valuable  to  us  is  the'  discovery 
of  functional  relations^  and  that  what  we  want  to  know  is 
merely  the  dependence  of  experiences  on  one  another.  It 
then  becomes  obvious  that  the  reference  to  unknown  funda- 
mental variables  which  are  not  given  (things-in-themselves) 
is  purely  fictitious  and  superfluous.  But  even  when  we 
allow  this  fiction,  uneconomical  though  it  be,  to  stand  at 
first,  we  can  still  easily  distinguish  different  classes  of  the 
mutual  dependence  of  the  elements  of  "  the  facts  of  con- 
sciousness " ;  and  this  alone  is  important  for  us. 


ABC  .  .  .  .   KLM  .  .  . 

a/37  .  .  . 

K'  L'  M'  .  .  . 

a'/3'7'  .  . 

K"  L"  M"  .  .  . 

a"  /3V  •   • 

The  system  of  the  elements  is  indicated  in  the  above 
scheme.  Within  the  space  surrounded  by  a  single  line  lie 
the  elements  which  belong  to  the  sensible  world, — the 
elements  whose  regular  connexion  and  peculiar  dependence 
on  one  another  represent  both  physical  (lifeless)  bodies  and 
the  bodies  of  men,  animals  and  plants.  All  these  elements, 
again,  stand  in  a  relation  of  quite  peculiar  dependence  to 


36          THE  ANALYSIS  OF  SENSATIONS 

certain  of  the  elements  K  L  M — the  nerves  of  our  body, 
namely  —  by  which  the  facts  of  sense-physiology  are 
expressed.  The  space  surrounded  by  a  double  line  con- 
tains the  elements  belonging  to  the  higher  psychic  life, 
memory-images  and  presentations,  including  those  which 
we  form  of  the  psychic  life  of  our  fellow-men.  These  may 
be  distinguished  by  accents.  These  presentations,  again, 
are  connected  with  one  another  in  a  different  way  (associa- 
tion, fancy)  from  the  sensational  elements  A  B  C  .  .'. 
K  L  M,  but  it  cannot  be  doubted  that  they  are  very  closely 
allied  to  the  latter,  and  that  in  the  last  resort  their  behaviour 
is  determined  by  A  B  C  .  .  .  K  L  M  (the  totality  of  the 
physical  world),  and  especially  by  our  body  and  nervous 
system.  The  presentations  a!  (3f  yr  of  the  contents  of  the 
consciousness  of  our  fellow-men  play  for  us  the  part  of 
intermediate  substitutions,  by  means  of  which  the  behaviour 
of  our  fellow-men, — the  functional  relation  of  K'  L'  M'  to 
A  B  C— becomes  intelligible,  in  so  far  as  in  and  for  itself 
(physically)  it  would  remain  unexplained. 

It  is  therefore  important  for  us  to  recognize  that  in  all 
questions  in  this  connexion,  which  can  be  intelligibly  asked 
and  which  can  interest  us,  everything  turns  on  taking  into 
consideration  different  ultimate  variables  and  different 
relations  of  dependence.  That  is  the  main  point.  Nothing 
will  be  changed  in  the  actual  facts  or  in  the  functional 
relations,  whether  we  regard  all  the  data  as  contents  of  con- 
sciousness, or  as  partially  so,  or  as  completely  physical.1 

1  Cf.  J.  Petzoldt's  excellent  paper  "  Solipsismus  auf  praktischem 
Gebiet"  (  Vierteljahrsschriftfiirwissentschaftliche  Philosophic,  XXXV. , 
3>  P-  339)»  Schuppe,  "  Der  Solipsismus"  (Zeitschr  fUr  immanente 
Philosophie,  Vol.  III.,  p.  327). 


J 


THE  ANALYSIS  OF  SENSATIONS          37 

The  biological  task  of  science  is  to  provide  the  fully 
developed  human  individual  with  as  perfect  a.  means  of 
orientating  himself  as  possible.  No  other  scientific  ideal 
can  be  realized,  and  any  other  must  be  meaningless. 

The  philosophical  point  of  view  of  the  average  man — if 
that  term  may  be  applied  to  his  naive  realism — has  a  claim 
to  the  highest  consideration.  It  has  arisen  in  the  process  of 
immeasurable  time  without  the  intentional  assistance  of  man. 
It  is  a  product  of  nature,  and  is  preserved  by  nature.  Every- 
thing that  philosophy  has  accomplished — though  we  may 
admit  the  biological  justification  of  every  advance,  nay,  of 
every  error — is,  as  compared  with  it,  but  an  insignificant 
and  ephemeral  product  of  art.  The  fact  is,  every  thinker, 
every  philosopher,  the  moment  he  is  forced  to  abandon  his 
one-sided  intellectual  occupation  by  practical  necessity, 
immediately  returns  to  the  general  point  of  view  of  man- 
kind. Professor  X.,  who  theoretically  believes  himself  to 
be  a  solipsist,  is  certainly  not  one  in  practice  when  he  has 
to  thank  a  Minister  of  State  for  a  decoration  conferred  upon 
him,  or  when  he  lectures  to  an  audience.  The  Pyrrhonist 
who  is  cudgelled  in  Moliere's  Le  Manage  Forc'e^  does  not  go 
on  saying  "  II  me  semble  que  vous  me  battez,"  but  takes 
his  beating  as  really  received. 

Nor  is  it  the  purpose  of  these  "  introductory  remarks  "  to 
discredit  the  standpoint  of  the  plain  man.  The  task  which 
we  have  set  ourselves  is  simply  to  show  why  and  for  what 
purpose  we  hold  that  standpoint  during  most  of  our  lives, 
and  why  and  for  what  purpose  we  are  provisionally  obliged 
to  abandon  it.  No  point  of  view  has  absolute,  permanent 
validity.  Each  has  importance  only  for  some  given  end. 


II.  ON  PRECONCEIVED  OPINIONS 
i. 

THE  physicist  has  frequent  occasion  to  observe  how 
greatly  our  knowledge  of  some  field  of  research  may 
be  hampered,  when,  instead  of  the  unprejudiced  investiga- 
tion of  that  field  for  its  own  sake,  views  are  transferred  to  it 
which  have  been  formed  in  some  other  department  of 
knowledge.  Far  more  serious  is  the  confusion  which  arises 
from  such  transference  of  preconceived  opinions  from  the 
field  of  physics  to  that  of  psychology.  Let  us  illustrate  this 
by  a  few  examples. 

A  physicist  observes  the  inverted  image  on  the  retina  of 
an  excised  eye,  and  puts  to  himself  very  naturally  the 
question,  How  does  a  point  situated  low  down  in  space 
come  to  be  reflected  on  the  upper  part  of  the  retina  ?  He 
answers  this  question  by  the  aid  of  studies  in  dioptrics.  If, 
now,  this  question,  which  is  perfectly  legitimate  in  the 
province  of  physics,  be  transferred  to  the  domain  of 
psychology,  only  obscurity  will  be  produced.  The  question 
why  we  see  inverted  retinal  images  the  right  way  up,  has  no 
meaning  as  a  psychological  problem.  The  light-sensations 
of  the  separate  spots  of  the  retina  are  connected  with  space- 
sensations  from  the  very  outset,  and  we  give  the  name 
"  above  "  to  those  positions  in  space  that  correspond  to  the 
parts  of  the  retina  situated  lower  down.  To  the  subject 

having  the  sensation  such  a  question  cannot  present  itself. 

38 


THE  ANALYSIS  OF  SENSATIONS          39 

It  is  the  same  with  the  well-known  theory  of  external 
projection.  The  problem  of  the  physicist  is,  to  find  the 
luminous  object-point  corresponding  to  a  point  on  the 
retinal  image,  by  prolonging  the  ray  that  passes  through  the 
point  on  the  image  and  the  centre  of  the  eye.  For  the 
subject  having  the  sensation  this  problem  does  not  exist,  as 
the  light  sensations  are  connected  from  the  beginning  with 
determinate  space-sensations.  The  entire  theory  of  the 
psychological  origin  of  the  external  world  by  the  projection 
of  sensations  outwards  is  founded  solely  on  a  mistaken 
application  of  physical  points  of  view.  Our  sensations  of 
sight  and  touch  are  bound  up  with  various  different  sensa- 
tions of  space ;  that  is  to  say,  they  exist  by  the  side  of  one 
another  and  outside  one  another,  exist,  in  other  words,  in  a 
spatial  field,  in  which  our  body  fills  but  a  part.  The  table, 
the  house,  the  tree,  lie  thus  self-evidently  outside  my  body. 
A  projection-problem  never  presents  itself,  is  neither 
consciously  nor  unconsciously  solved. 

A  physicist  (Mariotte)  discovers  that  a  certain  spot  on 
the  retina  is  blind.  The  physicist  is  accustomed  to 
correlate  with  every  spatial  point  a  point  on  the  retinal 
image,  and  with  every  point  on  the  image  a  sensation. 
Hence  the  question  arises,  What  do  we  see  at  the  points 
corresponding  to  the  blind  spot,  and  how  is  the  gap  filled 
out  ?  When  the  illegitimate  form  of  putting  the  question  in 
physical  terms  is  eliminated  from  the  psychological  inquiry, 
it  will  be  found  that  no  problem  exists  at  all  here.  We  see 
nothing  at  the  blind  spots,  the  gap  in  the  image  is  not  filled 
out,  or  rather,  the  gap  is  not  felt,  for  the  simple  reason  that 
a  defect  of  light-sensation  can  no  more  be  noticed  at  a  spot 
blind  from  the  beginning  than  the  blindness,  say,  of 


40  THE  ANALYSIS  OF  SENSATIONS 

the  skin  of  the  back  can  cause  a  gap  in  the  visual 
field. 

I  have  intentionally  chosen  simple  and  obvious  examples, 
as  they  can  best  make  clear  what  unnecessary  confusion  is 
caused  by  the  thoughtless  transference  of  a  conception  or 
mode  of  thought,  which  is  valid  and  serviceable  in  one  field, 
into  another  quite  different  field. 

In  the  work  of  a  celebrated  German  ethnographer  I 
recently  read  the  following  sentence :  "  This  tribe  has 
become  deeply  degraded  through  the  practice  of  canni- 
balism." By  its  side  lay  the  book  of  an  English  inquirer 
who  deals  with  the  same  subject.  The  latter  simply  puts 
the  question  why  certain  South-Sea  Islanders  are  cannibals, 
finds  out  in  the  course  of  his  inquiries  that  our  own 
ancestors  also  were  once  cannibals,  and  comes  to  under- 
stand the  position  the  Hindus  take  in  the  matter — a  point 
of  view  that  occurred  once  to  my  five-year-old  boy  who 
while  eating  a  piece  of  meat  stopped,  suddenly  shocked, 
and  cried  out,  "  We  are  cannibals  to  the  animals ! " 
"  Thou  shalt  not  eat  human  beings  "  is  a  very  praiseworthy 
maxim ;  but  in  the  mouth  of  the  ethnographer  it  destroys 
that  mild  and  sublime  glow  of  freedom  from  prepossession 
by  which  we  delight  to  recognize  the  true  inquirer.  But  a 
step  further,  and  we  shall  say,  "  Man  must  not  be  descended 
from  monkeys,"  <kThe  earth  ought  not  to  rotate,"  "Matter 
ought  not  to  fill  space  continuously,"  "  Energy  must  be 
constant,"  and  so  on.  I  believe  that  our  procedure  differs 
from  that  just  characterized  only  in  degree  and  not  in  kind, 
when  we  claim  absolute  validity  for  views  reached  in  the 
field  of  physics,  and  transfer  them  to  the  field  of  psychology 
without  having  first  tested  their  applicability.  In  such  cases 


THE  ANALYSIS  OF  SENSATIONS          41 

we  succumb  to  dogma,  if  not,  like  our  scholastic  forefathers, 
to  dogma  forced  upon  us  from  without,  yet  to  that  which 
we  have  created  ourselves.  And  what  result  of  research  is 
there  that  could  not  become  a  dogma  by  long  habit  ?  The 
very  skill  which  we  have  acquired  to  deal  with  constantly 
recurring  intellectual  situations  deprives  us  of  the  freshness 
and  open-mindedness  which  we  so  greatly  need  in  new 
situations. 

After  these  general  remarks,  I  may  perhaps  be  able 
to  explain  my  position  with  regard  to  the  dualism  of  the 
physical  and  the  psychical.  This  dualism  is  to  my  mind 
artificial  and  unnecessary. 


In  the  investigation  of  purely  physical  processes  we 
generally  employ  concepts  of  so  abstract  a  character 
that  as  a  rule  we  think  only  cursorily,  or  not  at  all, 
of  the  sensations  (elements)  that  lie  at  their  base.  For 
example,  when  I  ascertain  the  fact  that  an  electric  current 
having  the  intensity  of  i  ampere  develops  icj  cubic 
centimetres  of  oxyhydrogen  gas  at  o°  C.  and  760  mm. 
mercury-pressure  in  a  minute,  I  am  readily  disposed  to 
attribute  to  the  objects  defined  a  reality  wholly  inde- 
pendent of  my  sensations.  But  I  am  obliged,  in  order 
to  arrive  at  what  I  have  defined,  to  conduct  the  current, 
for  the  existence  of  which  my  sensations  are  my  only 
warrant,  through  a  circular  wire  having  a  definite  radius, 
so  that  the  current,  the  intensity  of  terrestrial  magnetism 
being  given,  shall  turn  the  magnetic  needle  a  certain 
angular  distance  out  of  the  meridian.  The  determina- 
tion of  the  magnetic  intensity,  of  the  volume  of  the 


42          THE  ANALYSIS  OF  SENSATIONS 

oxyhydrogen  gas,  etc.,  is  no  less  intricate.  The  whole 
statement  is  based  upon  an  almost  unending  series  of 
sensations,  particularly  if  we  take  into  consideration  the 
adjustment  of  the  apparatus,  which  must  precede  the 
actual  experiment.  Now  it  can  easily  happen  to  the 
physicist  who  does  not  study  the  psychology  of  his 
operations,  that  he  does  not  (to  reverse  a  well-known 
saying)  see  the  trees  for  the  wood,  that  he  overlooks 
the  sensory  elements  at  the  foundation  of  his  work. 
Now  I  maintain  that  every  physical  concept  means 
nothing  but  a  certain  definite  kind  of  connexion  of  the 
sensory  elements  which  I  have  denoted  by  A  B  C.  .  .  . 
These  elements — elements  in  the  sense  that  no  further 
resolution  has  as  yet  been  made  of  them — are  the 
simplest  materials  out  of  which  the  physical,  and  also 
the  psychological,  world  is  built  up. 

Physiological  research  also  may  be  of  a  purely  physical 
character.  I  can  follow  the  course  of  a  physical  process 
as  it  propagates  itself  through  a  sensitive  nerve  to  the 
central  organ ;  I  can  thence  trace  it  by  various  paths  to 
the  muscles,  whose  contraction  produces  new  physical 
changes  in  the  environment.  In  so  doing  I  am  precluded 
from  thinking  of  any  sensation  felt  by  the  man  or  animal 
under  observation ;  what  I  am  investigating  is  a  purely 
physical  object.  Very  much  is  lacking,  it  is  true,  to  our 
complete  comprehension  of  the  details  of  this  process, 
and  the  assurance  that  everything  depends  on  "the 
motion  of  molecules  "  can  neither  console  me  nor  deceive 
me  with  respect  to  my  ignorance. 

Long  prior  to  the  development  of  a  scientific  psychology 
people  had  nevertheless  perceived  that  the  behaviour  of 


THE  ANALYSIS  OF  SENSATIONS          43 

an  animal  under  physical  influences  can  be  predicted 
with  much  greater  accuracy,  i.e.,  can  be  better  under- 
stood, if  we  attribute  to  the  animal  sensations  and 
memories  like  our  own.  To  that  which  I  observe,  to  my 
sensations,  I  have  to  supply  mentally  the  sensations  of 
the  animal,  which  are  not  to  be  found  in  the  field  of 
my  own  sensations.  This  antithesis  appears  even  more 
abrupt  to  the  scientific  inquirer  who  is  investigating  a 
nervous  process  by  the  aid  of  colorless  abstract  concepts, 
and  is  required,  for  example,  to  add  mentally  to  that 
process  the  sensation  green.  This  last  may  actually 
appear  as  something  entirely  new  and  strange,  and  we 
ask  ourselves  how  it  is  that  this  miraculous  thing  is 
produced  from  chemical  processes,  electrical  currents, 
and  the  like. 


Psychological  analysis  has  taught  us  that  this  surprise 
is  unjustifiable,  since  the  physicist  is  always  operating 
with  sensations.  The  same  analysis  also  shows  us  that 
the  process  of  mentally  supplementing  complexes  of 
sensations  according  to  analogy  by  means  of  elements 
which  at  the  moment  are  not  being  observed,  or  by 
elements  which  cannot  possibly  be  observed,  is  one 
which  is  daily  practised  by  the  physicist ;  as,  for  example, 
when  he  imagines  the  moon  a  tangible,  inert,  heavy 
mass.  The  totally  strange  character  of  the  intellectual 
situation  above  described  is  therefore  an  illusion. 

There  is  also  another  consideration, — a  consideration 
confined  to  my  own  sensory  sphere, — which  serves  to 
dispel  the  illusion.  Before  me  lies  the  leaf  of  a  plant. 


44          THE  ANALYSIS  OF  SENSATIONS 

The  green  (A)  of  the  leaf  is  connected  with  a  certain 
optical  sensation  of  space  (B)>  with  a  sensation  of  touch 
(C),  and  with  the  visibility  of  the  sun  or  the  lamp  (Z>). 
If  the  yellow  (JE)  of  a  sodium  flame  takes  the  place  of 
the  sun,  the  green  (A)  will  pass  into  brown  (F).  If  the 
chlorophyl  granules  be  removed  by  alcohol, — an  operation 
which  can  be  represented,  like  the  preceding  one,  by 
elements, — the  green  (A)  will  pass  into  white  (G).  All 
these  observations  are  physical  observations.  But  the 
green  (A)  is  also  connected  with  a  certain  process  of  my 
retina.  There  is  nothing  to  prevent  me  in  principle  from 
investigating  this  process  in  my  own  eye  in  exactly  the 
same  manner  as  in  the  previous  cases,  and  from  reducing 
it  to  its  elements  X  Y  Z  .  .  .  If  there  are  difficulties  in 
doing  this  for  my  own  eye,  it  can  be  done  with  some  one 
else's  eye,  and  the  gap  filled  out  by  analogy,  exactly  as  in 
other  physical  investigations.  Now  in  its  dependence 
upon  BCD.  .  .  .,  A  is  a  physical  element,  in  its  depend- 
ence on  X  Y  Z  .  .  .  it  is  a  sensation,  and  can  also  be 
considered  as  a  psychical  element.  The  green  (A), 
however,  is  not  altered  at  all  in  itself,  whether  we  direct 
our  attention  to  the  one  or  to  the  other  form  of  depend- 
ence. I  see,  therefore,  no  opposition  of  physical  and 
psychical,  but  simple  identity  as  regards  these  elements. 
In  the  sensory  sphere  of  my  consciousness  everything  is 
at  once  physical  and  psychical  (cp.  p.  17). 


4- 

The  obscurity  of  this  intellectual  situation  has,  I  take  it, 
arisen  solely  from  the  transference  of  a  physical  preposses- 


THE  ANALYSIS  OF  SENSATIONS          45 

sion  to  the  field  of  psychology.  The  physicist  says :  I 
find  everywhere  bodies  and  the  motions  of  bodies  only, 
no  sensations  ;  sensations,  therefore,  must  be  something 
entirely  different  from  the  physical  objects  I  deal  with. 
The  psychologist  accepts  the  second  portion  of  this 
declaration.  For  him,  as  is  proper,  sensations  are  the 
primary  data ;  but  to  these  there  corresponds  a  mysterious 
physical  something  which,  conformably  with  the  pre- 
possession, must  be  quite  different  from  sensations.  But 
what  is  it  that  is  the  really  mysterious  thing  ?  Is  it  the 
Physis  or  the  Psyche  ?  Or  is  it  perhaps  both  ?  It  would 
almost  appear  so,  as  it  is  now  the  one  and  now  the  other 
that  appears  unattainable  and  involved  in  impenetrable 
obscurity.  Or  are  we  here  being  led  round  in  a  circle  by 
some  evil  spirit  ?  > 

I  believe  that  the  latter  is  the  case.  For  me  the 
elements  A  B  C ...  are  immediately  and  indubitably 
given,  and  for  me  they  can  never  afterwards  be  volatilized 
away  by  considerations  which  ultimately  are  always  based 
on  their  existence. 

The  task  of  specialized  investigation  in  the  sensory 
physico-psychical  sphere,  which  has  not  been  made 
superfluous  by  this  general  survey,  is  to  ascertain  the 
peculiar  method  of  combination  of  the  A  B  C  s.  This 
may  be  expressed  symbolically  by  saying  that  it  is  the 
object  of  special  research  to  find  equations  of  the  form 
f(AB  C  .  .  .)  =  o(zero). 


III.  MY  RELATION  TO  RICHARD 

AVENARIUS  AND  OTHER 

THINKERS. 

i. 

I  HAVE  already  alluded  to  points  at  which  the  views 
here  advocated  are  in  touch  with  those  of  various 
philosophers  and  philosophically  inclined  scientists.  A 
full  enumeration  of  these  points  of  contact  would  require 
me  to  begin  with  Spinoza.  That  my  starting-point  is  not 
essentially  different  from  Hume's  is  of  course  obvious.  I 
differ  from  Comte  in  holding  that  the  psychological  facts 
are,  as  sources  of  knowledge,  at  least  as  important  as  the 
physical  facts.  My  position,  moreover,  borders  closely  on 
that  of  the  representatives  of  the  philosophy  of  immanence. 
This  is  especially  true  in  the  case  of  Schuppe,  with  whose 
writings  I  became  acquainted  in  1902  ;  his  Outline  of 
Theory  of  Knoiuledge  and  Logic,  a  work  which  is  packed 
with  thought  and  which  can  be  read  without  a  special 
dictionary,  struck  a  particularly  sympathetic  chord  in  me. 
In  this  book  I  have  found  scarcely  anything  to  which, 
perhaps  with  some  small  modification,  I  cannot  yield  a 
hearty  assent.  To  be  sure,  his  conception  of  the  Ego 
constitutes  a  point  of  difference  between  us ;  but  not  a 
point  on  which  it  would  be  hopeless  to  reach  an  under- 
standing. As  to  the  views  of  Avenarius,  the  affinity 

between  them  and  my  own  is  as  great  as  can  possibly  be 

46 


THE  ANALYSIS  OF  SENSATIONS          47 

imagined  where  two  writers  have  undergone  a  different 
process  of  development,  work  in  different  fields,  and  are 
completely  independent  of  one  another.  The  agreement 
is  somewhat  obscured  by  the  great  difference  of  form. 
Avenarius  presents  us  with  a  scheme,  exhaustive  indeed 
but  highly  generalized,  which  is  made  more  difficult  to 
grasp  by  a  strange  and  unfamiliar  terminology.  For  con- 
structions of  this  kind  I  had  neither  occasion  nor  vocation, 
neither  inclination  nor  talent;  I  am  a  scientist  and  not 
a  philosopher.  What  I  aimed  at  was  merely  to  attain  a 
safe  and  clear  philosophical  standpoint,  whence  practicable 
paths,  shrouded  in  no  metaphysical  clouds,  might  be  seen 
leading  not  only  into  the  field  of  physics  but  also  into  that 
of  psycho-physiology.  With  the  attainment  of  this,  my 
battle  was  won.  Although  my  theory  is  the  fruit  of  long 
years  of  meditation  from  earliest  youth  upwards,  yet  in  its 
brevity  it  has  the  form  of  a  mere  aperfu,  nor  shall  I  be 
offended  if  it  is  regarded  in  that  light.  I  willingly  admit 
that  in  my  distaste  for  an  artificial  terminology  I  have 
perhaps  fallen  into  the  opposite  extreme  to  that  of  Avenarius. 
While  Avenarius  is  often  not  to  be  understood,  or  only 
to  be  understood  after  much  study,  my  words  have  often 
enough  been  misunderstood.  One  acute  critic  considers 
that  many  of  my  results  are  results  which  I  ought  not  to 
have  reached  (he  is  therefore  in  a  position  to  save  himself 
the  trouble  of  investigation,  since  he  already  knows  the 
results  to  which  investigation  ought  to  lead),  and  proceeds 
to  reproach  me  with  being  difficult  to  place,  since  I  use 
ordinary  language,  and  it  is  consequently  impossible  to  see 
to  what  "system"  I  adhere.  Thus,  first  and  foremost, 
you  have  to  choose  a  system ;  then  within  the  walls  of  that 


48          THE  ANALYSIS  OF  SENSATIONS 

system  you  may  think  and  speak.  In  this  way  all  kinds 
of  current  popular  views  have  been  comfortably  read  into 
my  words  ;  I  have  been  accused  of  idealism,  Berkeleyanism, 
even  of  materialism,  and  of  other  "  -isms,"  of  all  of  which 
I  believe  myself  to  be  innocent. 

The  fact  is  that  each  of  the  two  methods  of  exposition 
has  its  advantages  and  disadvantages.  But  the  difference 
of  form  has  had  a  prejudicial  effect  also  on  the  mutual 
understanding  between  Avenarius  and  myself.  I  recognized 
the  affinity  between  our  views  at  a  very  early  stage,  and 
expressed  my  conviction  of  it  in  the  Mechanik  (1883)  and 
in  the  first  edition  of  this  book  (1886),  although  at  that 
time  I  was  only  able  to  refer  to  one  of  Avenarius'  minor 
works  (Denken  der  Welt  nach  dem  Prinzip  des  kleinsten 
J^ra/f masses),  which  had  appeared  in  1876  and  had  acci- 
dentally come  in  my  way  shortly  before  the  publication  of 
my  Mechanik.  It  was  only  in  1888,  1891,  and  1894, 
by  means  of  Avenarius'  publications,  Kritik  der  reinen 
Erfahrung,  Der  menschliche  Weltbegriff,  and  his  psycho- 
logical articles  in  the  Vierteljahrsschrift,  that  the  similarity 
of  our  tendencies  was  fully  revealed  to  me.  As  to  the 
first  of  these  works,  however,  its  somewhat  hypermeta- 
phorical  terminology  prevented  me  from  tasting  the  full 
rapture  of  agreement.  It  is  asking  rather  much  of  an 
elderly  man  that  to  the  labour  of  learning  the  languages  of 
the  nations  he  should  add  that  of  learning  the  language  of 
an  individual.  It  was  consequently  reserved  for  the 
younger  generation  to  turn  the  work  of  Avenarius  to 
good  use :  in  this  connexion  I  am  glad  to  be  able  to  refer 
to  the  writings  of  H.  Cornelius,  C.  Hauptmann  and  J. 
Petzoldt,  which  are  in  a  fair  way  to  bring  to  light  and 


THE  ANALYSIS  OF  SENSATIONS          49 

to  develop  further  the  real  value  of  Avenarius'  work. 
Avenarius,  too,  acknowledged  on  his  side  the  affinity 
between  us,  and  noticed  it  in  the  books  that  appeared 
from  1888  to  1895.  Yet  with  him,  too,  the  conviction  of 
a  profounder  coincidence  of  view  between  us  seems,  as 
I  am  forced  to  infer  from  remarks  made  by  him  in  the 
past  to  third  persons,  only  to  have  been  developed 
gradually.  The  man  himself  I  have  never  known  person- 
ally. Unmistakable  efforts  are  being  made  to  minimize 
his  importance,  but,  in  spite  of  that,  acquaintance  with 
his  works  is,  I  am  glad  to  say,  on  the  increase, 


2. 

I  should  now  like  to  indicate  more  particularly  those 
points  of  agreement  between  us  to  which  I  attach  import- 
ance. The  economy  of  thought,  the  economical  repre- 
sentation of  the  actual, — this  was  indicated  by  me,  in 
summary  fashion  first  in  1871  and  1872,  as  being  the 
essential  task  of  science,  and  in  1882  and  1883  I  gave 
considerably  enlarged  expositions  of  this  idea.  As  I  have 
shewn  elsewhere,  this  conception,  which  implicitly  contains 
and  anticipates  KirchhofPs  notion  of  "perfectly  simple 
description"  (1874),  was  by  no  means  quite  new;  it  can 
be  traced  back  to  Adam  Smith,  and,  as  P.  Volkmann  holds, 
in  its  beginnings  even  to  Newton.  We  find  the  same  con- 
ception again,  with  the  exception  of  one  feature  that  does 
not  come  out  clearly,  fully  developed  in  Avenarius  (1876). 

A  broad  foundation  is  laid  for  the  theory  in  question, 
and  light  is  shed  upon  it  from  new  sides,  if,  in  conformity 
with  the  stimulus  given  by  Darwinism,  we  conceive  of  all 


50          THE  ANALYSIS  OF  SENSATIONS 

psychical  life — including  science — as  biological  appearance, 
and  if  we  apply  to  the  theory  the  Darwinian  conceptions  of 
struggle  for  existence,  of  development,  and  of  selection. 
The  theory  is  inseparable  from  the  hypothesis  that  each 
and  every  psychical  entity  is  physically  founded  and 
determined.  Now,  in  his  Kritik  der  reinen  Erfahrung, 
Avenarius  tries  to  shew  in  detail  that  all  theoretical  and 
practical  activity  is  determined  by  change  in  the  central 
nervous  system.  In  doing  this  he  is  merely  basing  him- 
self on  the  very  general  assumption  that  the  central  organ 
is  subject  to  an  impulse  of  self-preservation,  a  tendency  to 
maintain  its  equilibrium,  not  only  as  a  whole,  but  also  in 
its  parts.  This  agrees  very  well  with  the  conceptions 
developed  by  Hering  as  to  the  behaviour  of  living  sub- 
stance. In  holding  these  views,  Avenarius  is  brought  into 
close  contact  with  modern  positive  research,  particularly 
in  physiology.  In  my  writings  too,  opinions  of  a  corre- 
sponding nature,  briefly  indeed,  but  definitely  expressed, 
appeared  as  long  ago  as  1863,  and  in  1883  I  expounded 
these  opinions  at  greater  length,  though  without  develop- 
ing a  complete  system,  such  as  we  find  in  Avenarius. 

But  it  is  to  our  agreement  in  the  conception  of  the 
relation  between  the  physical  and  the  psychical  that  I 
attach  the  greatest  importance.  For  me  this  is  the  main 
point  at  issue.  It  was  by  means  of  his  psychological 
articles  that  I  first  became  convinced  of  this  coincidence 
between  Avenarius  and  myself.  In  order  to  be  sure  of 
making  no  mistake,  I  addressed  an  inquiry  on  the  subject 
to  Dr.  Rudolf  Wlassak,  who  I  knew  would  be  intimately 
acquainted  with  Avenarius'  standpoint,  thanks  to  his  associa- 
tion with  him  for  many  years.  His  reply  was  as  follows : — 


THE  ANALYSIS  OF  SENSATIONS          51 

"The  conception  of  the  relation  of  'the  physical'  to 
*  the  psychical '  is  identical  in  Avenarius  and  Mach.  Both 
come  to  the  conclusion  that  the  difference  between  the 
physical  and  the  psychical  consists  solely  in  the  difference 
of  the  relations  of  dependence,  which  on  the  one  hand  are 
the  objects  dealt  with  by  Physics  (in  the  widest  sense  of 
the  word),  and  on  the  other  are  the  objects  dealt  with  by 
psychology.  If  I  investigate  the  dependence  of  one  con- 
stituent (A)  of  an  environment  on  another  constituent  (£) 
of  an  environment,  I  am  studying  physics ;  if  I  inquire  to 
what  extent  A  is  changed  by  a  change  in  the  sense-organs 
or  the  central  nervous  system,  I  am  studying  psychology. 
Avenarius  has  accordingly  proposed  to  abolish  the  terms 
'  physical '  and  '  psychical '  and  in  future  only  to  speak  of 
physical  and  psychological  dependencies  ("Observations," 
Vierteljahrsschrift)  xix.,  p.  18).  In  Mach's  work  the  same 
view  occurs,  except  that  (?)  the  untenability  of  the  old 
conception  of  the  psychical,  and  consequently  of  the  proper 
task  of  psychology,  is  not  demonstrated. 

"  This  task  is  performed  by  the  exposure  of  '  Introjection/ 
or  rather  of  the  fallacy  in  formal  logic  which  underlies 
introjection.  Avenarius  starts  from  the  fact  that  naive 
realism,  'the  natural  view  of  the  world,'  stands  at  the 
beginning  of  all  philosophizing.  Within  the  limits  of  this 
natural  view  of  the  world  it  is  possible  for  a  relative 
delimitation  of  the  complex  'self  and  the  complex  'en- 
vironment '  to  be  carried  out  without  necessarily  involving 
the  'dualism'  of  'body'  and  'soul,'  since,  from  the 
standpoint  of  naive  realism,  the  constituents  that  belong  to 
the  'self,'  to  one's  own  body,  are  through  and  through 
comparable  with  the  constituents  of  the  environment. 


52          THE  ANALYSIS  OF  SENSATIONS 

Even  when  the  preliminary  survey  has  advanced  to  the 
formation  of  concepts  of  substance  (Mach,  Analysts  of 
Sensations^  p.  5),  this  does  not  mean  that  a  complete  and 
essential  difference  between  body  and  soul  is  given.  The 
final  splitting  up  of  the  world,  originally  conceived  by  naive 
realism  as  a  unity,  is  really  occasioned,  according  to 
Avenarius,  by  the  interpretation  of  the  utterances  of  our 
fellow-men.  As  long  as  I  say,  '  the  tree  does  not  exist  for 
me  alone ;  it  also,  as  their  utterances  permit  me  to  assume, 
exists  for  my  fellow-men  m»the  same  way  as  it  exists  for  me,' 
I  am  in  no  wise  overstepping  the  analogy  which  formal 
logic  allows  between  me  and  my  fellow-men.  But  I  am 
overstepping  this  analogy,  if  I  say  that  the  tree  exists  as 
*  a  copy,'  ( a  sensation '  or  '  a  presentation '  in  my  fellow- 
men,  if  I  introduce  or  introject  the  tree ;  since  I  am  then 
assuming  something  for  my  fellow-men  which  I  cannot  dis- 
cover in  my  own  experience,  which  always  shews  me  the 
constituents  of  my  environment  as  standing  in  a  definite 
relation  to  my  body,  and  never  as  being  in  my  consciousness 
or  the  like.  Inasmuch  as  introjection  is  a  way  of  passing 
beyond  experience,  every  attempt  to  bring  it  into  harmony 
with  the  facts  of  experience  must  become  an  inexhaustible 
'  source  of  pseudo-problems.  This  is  most  clearly  seen  in 
the  different  forms  which,  in  the  course  of  the  history  of 
philosophy,  introjection  has  assumed.  The  oldest  and 
crudest  theories  of  perception  exhibited  it  in  its  crudest  and 
simplest  form ;  they  supposed  that  copies  were  detached  from 
objects,  and  that  these  copies  penetrated  within  the  body. 
Now  in  so  far  as  it  is  recognized  that  the  constituents  of  the 
environment  are  not  present  inside  the  body  in  the  same 
way  as  they  are  present  outside  it,  to  that  extent  they  are 


THE  ANALYSIS  OF  SENSATIONS          53 

bound,  the  moment  they  are  inside  it,  to  become  something 
essentially  different  from  the  environment.  The  root  of 
dualism  lies  in  the  extension  of  introjection,  in  the  attempt  to 
bring  it  into  harmony  with  the  complex  of  the  environment. 
"  It  may  be  doubted  whether  Avenarius'  account  of  the 
motives  for  introjection  is  satisfactory  in  all  cases.  He 
holds  that  introjection  is  always  connected  with  the  ex- 
planation of  the  *  perceptions  '  of  one's  fellow-men.  But 
it  might  well  be  urged  that  the  fact  that  one  and  the  same 
constituent  of  the  environment  is  at  one  time  given  in 
sensations  as  a  'thing,'  and  at  another  given  as  a  memory, 
can  be  sufficient  motive  for  conceiving  this  constituent  as 
being  present  twice  over,  namely,  first  '  materially '  in  the 
environment,  and  secondly  in  my  'consciousness,'  in  my 
*  soul.'  Another  point  to  be  considered  is,  whether  dream- 
experiencies  cannot  equally  constitute,  at  a  primitive  stage 
of  culture,  an  independent  motive  for  dualism.1  Avenarius, 
indeed,  represents  introjection  as  the  presupposition  of  the 
dualist's  interpretation  of  dream-experiences,  but  without 
adducing  conclusive  reasons.  But  it  is  not  justifiable  to 
regard  prehistoric  animism  as  the  root  of  dualism,  if  by 
'  animism '  we  understand  merely  the  hypothesis  that  all 
the  lifeless  constituents  of  our  environment  are  beings  like 
ourselves.  As  long  as  deeper-lying  physiological  reasons 
do  not  make  it  impossible,  the  *  natural  view  of  the  world  ' 
can  also  provide  a  foundation  for  the  hypothesis  that,  in 
the  case  of  the  tree,  for  example,  the  constituents  of  its 
environment  exist  for  it  in  the  same  sense  as  they  do  for 
human  beings.  In  other  words :  Anyone  who  held  the 

1  According  to  Tylor,  they  are  in  fact  one  of  the  strongest  motives 
(Mach). 


54          THE  ANALYSIS  OF  SENSATIONS 

view  of  the  psychical  common  to  Avenarius  and  Mach, 
might,  if  he  were  entirely  ignorant  of  physiology,  suppose 
that  a  tree  or  a  stone  touches  and  sees  its  environment. 
In  that  case  he  would  still  not  be  a  dualist.  He  only 
becomes  a  dualist  when,  in  order  to  explain  this  touching 
and  seeing  on  the  part  of  the  tree  or  stone,  he  assumes  that 
the  constituents  of  the  environment,  which  the  tree  and 
stone  taste  and  see,  are  present  over  again  in  the  tree  as  its 
'  sensations '  or  its  '  consciousness/  It  is  only  then  that 
the  world  is  duplicated  by  division  into  a  spiritual  part  and 
a  material  part. 

"  The  discovery  of  the  illegitimacy  of  introjection  throws 
light  in  two  directions.  On  the  one  hand  it  is  illuminating 
on  the  side  of  theory  of  knowledge.  All  problems  con- 
nected with  the  relation  of  our  'sensations,'  'presenta- 
tions '  and  '  contents  of  consciousness '  to  the  material 
things,  of  which  the  above-mentioned  products  of  intro- 
jection are  supposed  to  be  the  'copies,'  'signs,'  and  so 
forth,  are  seen  to  be  merely  illusory.  Instances  of  such 
pseudo-problems  are  the  problems  as  to  projection  which 
we  meet  in  theories  of  space,  the  exteriorization  of  the 
space-sensations,  etc. 

"  On  the  other  hand,  the  elimination  of  introjection  implies 
that  all  psychology  which  is  not  physiological  is  illegitimate. 
When  I  have  recognized  that  the  '  contents  of  conscious- 
ness,' the  'psychic  processes,'  which  accompany  changes 
in  the  nervous  system,  are  nothing  more  than  constituents 
of  my  environment  which  I  have  introduced  into  my  fellow- 
men  and  ultimately  also  into  myself,  it  is  impossible  for 
me  to  look  for  anything  in  the  nervous  system  except 
physiological  processes.  All  special  psychical  causality 


THE  ANALYSIS  OF  SENSATIONS          55 

disappears ;  all  those  problems  disappear  which  are  con- 
nected with  the  question  whether  the  intervention  of 
psychical  forces  in  the  physiological  processes  of  the  brain 
is  compatible  with  the  principle  of  the  conservation  of 
energy.1 

"  When  such  a  phrase  is  used  as  '  the  continued  existence 
of  presentations  without  their  being  in  consciousness ' 
(Mach,  Wdrmekhre  p.  441),  this  is,  strictly  speaking,  only 
legitimate  as  an  abbreviated  expression  for  particular 
processes  of  the  central  nervous  system,  and  in  any  case  it 
savours  strongly  of  dualistic  conceptions." 

The  remaining  difference  between  the  way  in  which 
Avenarius  puts  his  views  and  the  way  in  which  I  put  mine 
can  be  reduced  to  elements  which  are  easily  grasped.  In 
the  first  place,  it  was  not  my  intention  to  give  a  complete 
exposition  of  the  development  of  my  point  of  view  out 
of  the  preceding  phrases  of  philosophical  reflection  about 
the  world.  In  the  second  place,  Avenarius  starts  from  a 

1  I  cannot  refrain  from  here  expressing  my  surprise  that  the  principle 
of  the  conservation  of  energy  has  so  often  been  dragged  in  in  connexion 
with  the  question  whether  there  is  a  special  psychical  agent.  On  the 
assumption  that  energy  is  constant,  the  course  of  physical  processes  is 
limited,  but  not  necessarily  determined  with  perfect  uniqueness.  That 
the  principle  of  conservation  of  energy  is  satisfied  in  all  physiological 
cases,  merely  tells  us  that  the  soul  neither  uses  up  work  nor  performs 
it.  For  all  that,  the  soul  may  still  be  a  partly  determinant  factor. 
When  the  philosopher  asks  a  question  which  has  reference  to  this  case, 
he  usually  misses  the  point  of  the  principle  of  the  conservation  of 
energy,  and  the  stock  reply  of  the  physicist  has  no  intelligible  meaning 
in  relation  to  a  case  so  far  removed  from  the  scope  of  his  ideas.  Cp. 
the  references  to  a  similar  discussion  in  Hofler's  Psychologic,  1897, 
pp.  58  sqq.,  note.  Apart  from  the  above  considerations,  the  assump- 
tion of  a  special  psychical  agent  appears  to  me  to  be  a  presupposition 
which  is  unfortunate  and  can  only  do  harm  by  making  investigation 
difficult ;  it  is  moreover  unnecessary  and  improbable  (Mach). 


56          THE  ANALYSIS  OF  SENSATIONS 

realistic  phase ;  I,  on  the  other  hand,  started  from  an  idealist 
phase  (p.  30,  above,  footnote),  such  as  I  actually  went 
through  in  my  early  youth.  In  that  way  I  might  easily  have 
talked,  for  instance,  about  the  elimination  of  "  extrajection  " 
(pp.  6,  12-22,  29-35,  43>  above).  In  the  third  place,  it  is 
not  necessary  to  attribute  so  important  a  role  to  the  inter- 
pretation of  our  fellow-men  by  means  of  introjection  in  the 
bad  sense,  until  after  the  new  standpoint  has  been  reached  \ 
and  then  it  is  also  not  necessary  to  exclude  this  introjection 
again.  A  solitary  thinker  might  reach  the  new  standpoint, 
and  even  he,  as  Wlassak  observes,  might  have  to  rise 
superior  to  dualistic  tendencies.  But  this  standpoint  once 
reached,  and  the  varying  character  of  the  dependence .  of 
the  elements  once  recognized  as  the  essential  point,  the 
question  whether  we  start  from  a  phase  of  realism  or  of 
idealism  is  of  no  greater  importance  for  us  than  a  change 
in  the  fundamental  variables  of  his  equations  is  for  the 
mathematician  or  physicist. 

What  Avenarius  puts  forward,  and  consequently  what  I 
also  put  forward,  appears  to  me  to  contain  scarcely  any- 
thing that  is  not  self-evident — self-evident  at  least  for  every 
man  who  has  shaken  himself  free  from  the  pressure  of  "  the 
legacy  of  wild  philosophy,"  as  Tylor  calls  it.  Science  has 
always  required  such  self-evident  propositions  as  a  safe 
foundation  upon  which  to  build.  When  I  see  the  paths 
pursued  by  different  philosophical  thinkers  converging,  and 
especially  when  I  contemplate  the  close  coincidence 
between  general  philosophical  views  and  the  views  of 
scientific  specialists,  I  think  that  I  am  justified  in  detecting 
here  a  hopeful  presage  of  the  mutual  accommodation  of 
the  sciences  to  one  another. 


IV.  THE  CHIEF  POINTS  OF  VIEW 
FOR  THE  INVESTIGATION  OF 
THE  SENSES. 


i. 


IN  order  to  get  our  bearings,  we  will  now  try  to  obtain, 
from  the  standpoint  we  have  reached,  a  broad  view 
of  the  special  problems  that  will  engage  our  attention. 

When  once  the  inquiring  intellect  has  formed,  through 
adaptation,  the  habit  of  connecting  two  things,  A  and 
B ,  in  thought,  it  tries  to  retain  this  habit  as  far  as  pos- 
sible, even  where  the  circumstances  are  slightly  altered. 
Wherever  A  appears,  B  is  added  in  thought.  The  prin- 
ciple thus  expressed,  which  has  its  root  in  an  effort  for 
economy,  and  is  particularly  noticeable  in  the  work  of  the 
great  investigators,  may  be  termed  the  principle  of  continuity . 

Every  actually  observed  variation  in  the  connexion  of  A 
and  B  which  is  sufficiently  large  to  be  noticed  makes  itself 
felt  as  a  disturbance  of  the  above-mentioned  habit,  and 
continues  to  do  so  until  the  habit  is  sufficiently  modified 
to  prevent  the  disturbance  being  felt.  Suppose,  for  in- 
stance, that  we  have  become  accustomed  to  seeing  light 
deflected  when  it  impinges  on  the  boundary  between  air  and 
glass.  But  these  deflections  vary  noticeably  in  different 
tiases,  and  the  habit  formed  by  observing  some  cases 
cannot  be  transferred  undisturbed  to  new  cases,  until  we 
are  able  to  associate  with  every  particular  angle  of  in- 
cidence (A)  a  particular  angle  of  refraction  (B\  which  we 

57 


58          THE  ANALYSIS  OF  SENSATIONS 

are  able  to  do  by  discovering  the  so-called  law  of  refraction, 
and  by  making  ourselves  familiar  with-  the  rules  contained 
in  that  law.  Thus  another  and  modifying  principle  con- 
fronts that  of  continuity ;  we  will  call  it  the  principle  of 
sufficient  determination,  or  sufficient  differentiation. 

The  joint  action  of  the  two  principles  may  be  very  well 
illustrated  by  a  further  analysis  of  the  example  cited.  In 
order  to  deal  with  the  phenomena  exhibited  in  the  change 
of  color  of  light,  the  idea  of  the  law  of  refraction  must  be 
retained,  but  with  every  particular  color  a  particular  index 
of  refraction  must  be  associated.  We  soon  perceive  that 
with  every  particular  temperature  also,  a  particular  index  of 
refraction  must  be  associated ;  and  so  on. 

In  the  end,  this  process  leads  to  temporary  contentment  and 
satisfaction,  the  two  things  A  and  B  being  conceived  as  so  con- 
nected that  to  every  change  of  the  one  that  can  be  observed  at 
any  moment  there  corresponds  an  appropriate  change  of  the 
other.  It  may  happen  that  both  A  and  B  are  conceived  as 
complexes  of  components,  and  that  to  every  particular  com- 
ponent ofAa.  particular  component  of  B  corresponds.  This 
occurs,  for  example,  when  B  is  a  spectrum,  and  A  the  cor- 
responding sample  of  a  compound  to  be  tested,  in  which  case 
to  every  component  part  of  the  spectrum  one  of  the  com- 
ponents of  the  matter  volatilized  before  the  spectroscope  is 
correlated,  independently  of  the  others.  Only  through  com- 
plete familiarity  with  this  relation  can  the  principle  of  sufficient 
determination  be  satisfied. 

2. 

Suppose,  now,  that  we  are  considering  a  color-sensation 
B,  not  in  its  dependence  on  A,  the  heated  matter  tested, 


THE  ANALYSIS  OF  SENSATIONS          59 

but  in  its  dependence  on  the  elements  of  the  retinal  process, 
N.  By  doing  this  we  change,  not  the  kind,  but  only  the  direc- 
tion of  our  point  of  view.  None  of  the  preceding  observations 
lose  their  force,  and  the  principles  to  be  followed  remain  the 
same.  And  this  holds  good,  of  course,  of  all  sensations. 

Now,  sensation  may  be  analysed  in  itself,  immediately, 
that  is,  psychologically  (which  was  the  course  adopted  by 
Johannes  Millie r),  or  the  physical  (physiological)  processes 
correlated  with  it  may  be  investigated  according  to  the 
methods  of  physics  (the  course  usually  preferred  by  the 
modern  school  of  physiologists),  or,  finally,  the  connexion 
of  psychologically  observable  data  with  the  corresponding 
physical  (physiological)  processes  may  be  followed  up — a 
mode  of  procedure  which  will  carry  us  farthest,  since  in  this 
method  observation  is  directed  to  all  sides,  and  one  investi- 
gation serves  to  support  the  other.  We  shall  endeavor  to 
attain  this  last-named  end  wherever  it  appears  practicable. 

This  being  our  object,  then,  it  is  evident  that  the  principle 
of  continuity  and  that  of  sufficient  determination  can  be  satis- 
fied only  on  the  condition  that  with  the  same  B  (this  or  that 
sensation)  we  always  associate  the  same  N  (the  same  nerve- 
process)  and  discover  for  every  observable  change  of  B  a  cor- 
responding change  of  N.  \iB  is  psychologically  analysable 
into  a  number  of  independent  components,  then  we  shall  rest 
satisfied  only  on  the  discovery,  in  N, of  equivalent  components 
corresponding  to  these.  If,  on  the  other  hand,  properties  or 
aspects  have  to  be  noticed  in  B  which  cannot  appear  in  isola- 
tion, as,  for  instance,  pitch  and  intensity  in  tones,  we  shall 
have  to  expect  the  same  state  of  things  in  N.  In  a  word, 
for  all  psychically  observable  details  of  B  we  have  to  seek 
the  correlated  physical  details  of  N. 


60          THE  ANALYSIS  OF  SENSATIONS 

I  do  not  of  course  maintain  that  a  (psychologically) 
simple  sensation  cannot  also  be  conditioned  by  very 
complicated  circumstances.  For  the  circumstances  would 
hang  together  like  the  links  of  a  chain  and  would  not  issue 
in  a  sensation,  unless  the  chain  extended  to  the  nerve. 
But  since  the  sensation  may  also  appear  in  the  form  of  a 
hallucination,  namely  when  no  physically  conditioned 
circumstances  are  present  outside  the  body,  we  see  that  a 
certain  nervous  process,  as  the  final  link  in  the  chain,  is 
the  essential  and  immediate  condition  of  the  sensation. 
Now  we  cannot  think  of  this  immediate  condition  as 
being  varied  without  conceiving  of  the  sensation  as  being 
varied,  and  vice  versa.  For  the  connexion  between  this  final 
link  and  the  sensation  we  will  regard  the  principle  which 
we  have  laid  down  as  valid. 


We  may  thus  establish  a  guiding  principle  for  the 
investigation  of  the  sensations.  This  may  be  termed  the 
principle  of  the  complete  parallelism  of  the  psychical  and 
physical.  According  to  our  fundamental  conception,  which 
recognizes  no  gulf  between  the  two  provinces  (the 
psychical  and  the  physical),  this  principle  is  almost  a  matter 
of  course  ;  but  we  may  also  enunciate  it,  as  I  did  years  ago, 
without  the  help  of  this  fundamental  conception,  as  a 
heuristic  principle  of  research.1 

The  principle  of  which  I  am  here  making  use  goes  further 
than  the  widespread  general  belief  that  a  physical  entity  cor- 
responds to  every  psychical  entity  and  vice  versa  ;  it  is  much 

1  Compare  ifiy  paper,  Ueber  die  Wirkung  der  raumlichen  Vertheilung 
des  Lichtreizes  aufdie  Netzhaut  (Sitzungsberichte  der  Wiener  Akadamie, 


THE  ANALYSIS  OF  SENSATIONS          61 

more  specialized.  The  general  belief  in  question  has  been 
proved  to  be  correct  in  many  cases,  and  may  be  held  to  be  pro- 
bably correct  in  all  cases ;  it  constitutes  moreover  the  neces- 
sary presupposition  of  all  exact  research.  At  the  same  time 
the  view  here  advocated  is  different  from  Fechner's  concep- 
tion of  the  physical  and  psychical  as  two  different  aspects 
of  one  and  the  same  reality.  In  the  first  place,  our  view 
has  no  metaphysical  background,  but  corresponds  only 
to  the  generalized  expression  of  experiences.  Again,  we 
refuse  to  distinguish  two  different  aspects  of  an  unknown 
tertium  quid ;  the  elements  given  in  experience,  whose  con- 
nexion we  are  investigating,  are  always  the  same,  and 
are  of  only  one  nature,  though  they  appear,  according  to 
the  nature  of  the  connexion,  at  one  moment  as  physical 
and  at  another  as  psychical  elements.1  I  have  been  asked 
whether  the  parallelism  between  psychical  and  physical  is 
not  meaningless  and  a  mere  tautology,  if  the  psychical  and 
physical  are  not  regarded  as  essentially  different.  The 
question  arises  from  a  misunderstanding  of  the  analysis 
which  I  have  given  above.  When  I  see  a  green  leaf  (an 

Vol.  LIL,  1865)  ;  further  Reichert's  und  Dtibois'  Archiv,  1865,  p.  634, 
and  Grundlinien  der  Lehre  von  den  Bewegimgsempfindungen  (Leipzig, 
Engelmann,  1875,  p.  63).  The  principle  is  also  implicitly  contained  in 
an  article  of  mine  in  Fichte's  Zeitschrift  filr  Philosophic  (Vol.  XLVI., 
1865,  p.  5),  which  is  printed  also  in  my  Popular  Scientific  Lectures , 
Chicago,  Open  Court  Publishing  Co. 

1  For  the  various  aspects  of  the  problem  of  parallelism,  see  C. 
Stumpf's  address  to  the  Psychological  Congress  at  Munich  (Munich, 
1897);  G.  Heymans,  "Zur  Parallelismusfrage,"  Zeitschrift  filr 
Psychologie  der  Sinnesorgane,  Vol.  XVII.  ;  O.  Kiilpe,  Ueber  die  Bezie- 
hung  z-wischen  kb'rpcrlichen  und  seelischen  Vorgangen,  Zeitschrift  fur 
Hypnotismus,  Vol.  VII.,  J.  von  Kries,  Uber  die  materiellen  Grund- 
lagen  der  Bewiisstseinserscheimmgen^  Freiburg  im  Breisgau,  1898;  C. 
Hauptmann,  Die  Metaphysik  in  der  Psychologie ',  Dresden,  1893. 


62          THE  ANALYSIS  OF  SENSATIONS 

event  which  is  conditioned  by  certain  brain-processes)  the 
leaf  is  of  course  different  in  its  form  and  color  from  the 
forms,  colors,  etc.,  which  I  discover  in  investigating  a 
brain,  although  all  forms,  colors,  etc.,  are  of  like  nature 
in  themselves,  being  in  themselves  neither  psychical  nor 
physical.  The  leaf  which  I  see,  considered  as  dependent 
on  the  brain-process,  is  something  psychical,  while  this 
brain-process  itself  represents,  in  the  connexion  of  its 
elements,  something  physical.  And  the  principle  of 
parallelism  holds  good  for  the  dependence  of  the  former 
immediately  given  group  of  elements  on  the  latter  group, 
which  is  only  ascertained  by  means  of  a  physical 
investigation  which  may  be  extremely  complicated  (cp. 
p.  44). 


I  have  perhaps  stated  the  principle  in  rather  too  abstract 
a  form.  A  few  concrete  examples  may  now  help  to  explain 
it.  Wherever  I  have  a  sensation  of  space,  whether  through 
the  sensation  of  sight  or  through  that  of  touch,  or  in 
any  other  way,  I  am  obliged  to  assume  the  presence  of 
a  nerve-process  of  the  same  kind  in  all  cases.  For  all 
time-sensations,  also,  I  must  suppose  like  nerve-processes. 

If  I  see  figures  which  are  the  same  in  size  and  shape 
but  differently  colored,  I  seek,  in  connexion  with  the 
different  color-sensations,  certain  identical  space-sensations 
and  corresponding  identical  nerve  -  processes.  If  two 
figures  are  similar  (that  is,  if  they  yield  partly  identical 
space-sensations)  then  the  corresponding  nerve-processes 
also  contain  partly  identical  components.  If  two  different 
melodies  have  the  same  rhythm,  then,  side  by  side  with 


THE  ANALYSIS  OF  SENSATIONS          63 

the  different  tone-sensations  there  exists  in  both  cases  an 
identical  time-sensation  with  identical  corresponding  nerve- 
processes.  If  two  melodies  of  different  pitch  are  identical, 
then  the  tone-sensations  as  well  as  their  physiological  con- 
ditions, have,  in  spite  of  the  different  pitch,  identical 
constituents.  If  the  seemingly  limitless  multiplicity  of 
color-sensations  is  susceptible  of  being  reduced,  by  psycho- 
logical analysis  (self-observation),  to  six  elements  (funda- 
mental sensations),  a  like  simplification  may  be  expected 
for  the  system  of  nerve-processes.  If  our  system  of  space- 
sensations  appears  in  the  character  of  a  threefold  manifold, 
the  system  of  the  correlated  nerve-processes  will  likewise 
present  itself  as  such. 


This  principle  has,  moreover,  always  been  more  or  less 
consciously,  more  or  less  consistently,  followed. 

For  example,  when  Helmholtz 1  assumes  for  every  tone- 
sensation  a  special  nerve-fibre  (with  its  appurtenant  nerve- 
process),  when  he  resolves  clangs,  or  compound  sounds, 
into  tone  -  sensations,  when  he  reduces  the  affinity  of 
compound  tones  to  the  presence  of  like  tone-sensations 
(and  nerve-processes),  we  have  in  this  method  of  procedure  a 
practical  illustration  of  our  principle.  It  is  only  the  applica- 
tion that  is  not  complete,  as  will  be  later  shown.  Brewster,2 

1  Helmholtz,    Die  Lehre    von    den    Tonempfimkingen,    Brunswick, 
Vieweg,    1863.      English   translation    by   Alex.    J.    Ellis,    London, 
Longmans,  Green,  &  Co.,  2nd  edition,   1885. 

2  Brewster,  A  Treatise  on  Optics,  London,  1831.    Brewster  regarded 
the  red,  yellow,  and  blue   light  as  extending  over  the  whole  solar 
spectrum,  though  distributed  there  with  varying  intensity,  so   that, 
to  the  eye,  red  appears  at  both  ends  (the  red  and  the  violet),  yellow 
in  the  middle,  and  blue  at  the  end  of  greater  refrangibility, 


64          THE  ANALYSIS  OF  SENSATIONS 

guided  by  a  psychological  but  defective  analysis  of  color- 
sensations,  and  by  imperfect  physical  experiments,1  was 
led  to  the  view  that,  corresponding  to  the  three  sensations, 
red,  yellow,  and  blue,  there  existed  likewise  physically 
only  three  kinds  of  light,  and  that,  therefore,  Newton's 
assumption  of  an  unlimited  number  of  kinds  of  light,  with 
a  continuous  series  of  refractive  indices,  was  erroneous. 
Brewster  might  easily  fall  into  the  error  of  regarding  green 
as  a  compound  sensation.  But  had  he  reflected  that  color- 
sensations  may  occur  entirely  without  physical  light,  he 
would  have  confined  his  conclusions  to  the  nerve-process 
and  left  untouched  Newton's  assumptions  in  the  province  of 
physics,  which  are  as  well  founded  as  his  own.  Thomas 
Young  corrected  this  error,  at  least  in  principle.  He 
perceived  that  an  unlimited  number  of  kinds  of  physical 
light  with  a  continuous  series  of  refractive  indices  (and  wave- 
lengths) was  compatible  with  a  small  number  of  color- 
sensations  and  nerve-processes, — that  a  discrete  number  of 
color-sensations  did  answer  to  the  continuum  of  deflexions 
in  the  prism  (to  the  continuum  of  the  space-sensations). 
But  even  Young  did  not  apply  the  principle  with  full 
consciousness  or  strict  consistency,  wholly  apart  from  the 
fact  that  he  allowed  himself  to  be  misled,  in  his  psycho- 
logical analysis,  by  physical  prejudices.  Even  he  first 
assumed,  as  fundamental  sensations,  red,  yellow,  and  blue, 
for  which  he  later  substituted  red,  green,  and  violet — 
misled,  as  Alfred  Mayer,  of  Hoboken,  has  admirably 

1  Brewster  believed  that  he  was  able  to  alter  by  absorption  the 
nuances  of  the  spectrum — colors  regarded  by  Newton  as  simple — 
a  result  which,  if  correct,  would  really  destroy  the  Newtonian  con- 
ception. He  experimented,  however,  as  Helmholtz  (Physiological 
Optics)  has  shown,  with  an  impure  spectrum. 


THE  ANALYSIS  OF  SENSATIONS          65 

shown,1  by  a  physical  error  of  Wollaston's.  The  direction 
in  which  the  theory  of  color- sensation,  which  has  reached  a 
high  degree  of  perfection  through  Hering,  has  still  to  be 
modified,  was  pointed  out  by  me  many  years  ago  in 
another  place. 

6. 

Here  I  will  merely  state  shortly  what  I  have  to  say 
concerning  the  treatment  of  the  theory  of  color-sensation. 
We  frequently  meet  with  the  assertion,  in  recent  works,  that 

1  Philosophical  Magazine,  February  1876,  p.  in.  Wollaston  was 
the  first  to  notice  (1802)  the  dark  lines  of  the  spectrum,  later  named 
after  Fraunhofer,  and  believed  that  he  saw  his  narrow  spectrum  divided 
by  the  strongest  of  these  lines  into  a  red,  a  green,  and  a  violet  part. 
He  regarded  these  lines  as  the  dividing  lines  of  the  physical  colors. 
Young  took  up  this  conception,  and  substituted  for  his  fundamental 
sensations  red,  yellow,  and  blue,  the  colors  red,  green,  and  violet. 
Thus,  in  his  first  conception,  Young  regarded  green  as  a  composite 
sensation,  in  his  second,  both  green  and  violet  as  simple.  The  question- 
able results  which  psychological  analysis  may  thus  yield,  are  well 
calculated  to  destroy  belief  in  its  usefulness  in  general.  But  we  must 
not  forget  that  there  is  no  principle  in  the  application  of  which  error  is 
excluded.  Here,  too,  practice  must  determine.  The  circumstance 
that  the  physical  conditions  of  sensation  almost  always  give  rise  to 
composite  sensations,  and  that  the  components  of  sensation  seldom 
make  their  appearance  separately,  renders  psychological  analysis  very 
difficult.  Thus,  green  is  a  simple  sensation  ;  a  given  pigment  or 
spectrum-green,  however,  will  as  a  rule  excite  also  a  concomitant 
yellow  or  blue  sensation,  and  thus  favor  the  erroneous  idea  (based 
upon  the  results  of  pigment-mixing)  that  the  sensation  of  green  is 
compounded  of  yellow  and  blue.  Careful  physical  study,  therefore,  is 
also  an  indispensable  requisite  of  psychological  analysis.  On  the  other 
hand,  physical  observation  must  not  be  overestimated.  The  mere 
observation  that  a  yellow  and  blue  pigment  mixed,  yield  a  green  pig- 
ment, cannot  by  itself  determine  us  to  see  yellow  and  blue  in  green, 
unless  one  or  the  other  color  is  actually  contained  in  it.  Certainly  no 
one  sees  yellow  and  blue  in  white,  although,  as  a  fact,  spectrum-yellow 
and  spectrum-blue  mixed  give  white. 
B 


66          THE  ANALYSIS  OF  SENSATIONS 

the  six  fundamental  color-sensations,  white,  black,  red, 
green,  yellow,  blue,  which  Hering  adopted,  were  first 
proposed  by  Leonardo  da  Vinci,  and  later  by  Mach  and 
Aubert.  From  the  very  first  it  seemed  to  me  highly 
probable,  in  view  of  the  conceptions  prevalent  at  this  time, 
that  the  assertion  was  founded  upon  an  error,  as  far  as 
Leonardo  da  Vinci  was  concerned.  Let  us  hear  what  he 
himself  says  in  his  Book  of  Painting  (Nos.  254  and  255  in 
the  translation  of  Heinrich  Ludwig,  Quellenschriften  zur 
Kunstgeschichte,  Vienna,  Braumiiller,  1882,  Vol.  XVIII. ). 
"  254.  Of  simple  colors  there  are  six.  The  first  of  these 
is  white,  although  philosophers  admit  neither  white  nor 
black  into  the  number  of  colors,  since  the  one  is  the  cause 
of  color,  the  other  of  its  absence.  But,  inasmuch  as  the 
painter  cannot  do  without  them,  we  shall  include  these  two 
also  among  the  other  colors  and  say  that  white  in  this 
classification  is  the  first  among  the  simple  colors,  yellow 
the  second,  green  the  third,  blue  the  fourth,  red  the  fifth, 
black  the  sixth.  And  the  white  we  will  let  represent  the 
light,  without  which  one  can  see  no  color,  the  yellow  the 
earth,  the  green  the  water,  blue  the  air,  red  fire,  and  black 
the  darkness  which  is  above  the  element  of  fire,  because  in 
that  place  there  is  no  matter  or  solid  substance  upon  which 
the  sunbeams  can  exert  their  force,  and  which  as  a  result 
they  might  illumine."  "255.  Blue  and  green  are  not 
simple  colors  by  themselves.  For  blue  is  composed  of 
light  and  darkness,  as,  the  blue  of  the  air,  which  is  made 
up  of  the  most  perfect  black  and  perfectly  pure  white." 
"  Green  is  composed  of  a  simple  and  a  composite  color, 
namely,  of  yellow  and  blue."  This  will  suffice  to  show  that 
Leonardo  da  Vinci  is  concerned  partly  with  observations 


THE  ANALYSIS  OF  SENSATIONS          67 

concerning  pigments,  partly  with  conceptions  of  natural 
philosophy,  but  not  with  the  subject  of  fundamental  color- 
sensations.  The  many  remarkable  and  subtle  scientific 
observations  of  all  sorts  which  are  contained  in  Leonardo 
da  Vinci's  book  lead  to  the  conviction  that  the  artists,  and 
among  them  especially  he  himself,  were  the  true  forerunners 
of  the  great  scientists  who  came  soon  afterwards,  These 
men  were  obliged  to  understand  nature  in  order  to  reproduce 
it  agreeably;  they  observed  themselves  and  others  in  the 
interest  of  pure  pleasure.  Yet  Leonardo  was  far  from  being 
the  author  of  all  the  discoveries  and  inventions  which 
Groth,  for  example  (Leonardo  da  Vinci  ah  Ingenieur  und 
Philosophy  Berlin,  1874),  ascribes  to  him.1  My  own 
scattered  remarks  concerning  the  theory  of  color-sensations 
were  perfectly  clear.  I  assumed  the  fundamental  sensations 
white,  black,  red,  yellow,  green,  blue,  and  six  different 
corrresponding  (chemical)  processes  (not  nerve-fibres)  in 
the  retina.  (Compare  Reicherfs  und  Dubois1  Archiv^  1865, 
P'  633,  et  seq.)  As  a  physicist,  I  was  of  course  familiar 
with  the  relation  of  the  complementary  colors.  My  con- 
ception, however,  was  that  the  two  complementary  processes 
together  excited  a  new — the  white — process.  (Loc.  cit.t 
p.  634.)  I  gladly  acknowledge  the  great  advantages  of 
Hering's  theory.  They  consist  for  me  in  the  following. 
First,  the  black  process  is  regarded  as  a  reaction  against  the 
white  process ;  I  can  appreciate  all  the  better  the  facilita- 
tion involved  in  this,  as  it  was  just  the  relation  of  black 
and  white  that  for  me  presented  the  greatest  difficulty. 
Further,  red  and  green,  as  also  yellow  and  blue,  are 

1  Marie  Herzfeld,  Leonardo  da   Vinci,  Auswahl  aus  den  veroffent- 
lichten  Handschriften^  Leipzig,  1904. 


68          THE  ANALYSIS  OF  SENSATIONS 

regarded  as  antagonistic  processes  which  do  not  produce 
a  new  process,  but  mutually  annihilate  each  other.  Ac- 
cording to  this  conception  white  is  not  subsequently 
produced  but  is  already  present  beforehand,  and  still 
survives  on  the  annihilation  of  a  color  by  the  comple- 
mentary color.  The  only  point  that  still  dissatisfies  me 
in  Hering's  theory  is  that  it  is  difficult  to  perceive  why 
the  two  opposed  processes  of  black  and  white  may  be 
simultaneously  produced  and  simultaneously  felt,  while 
such  is  not  the  case  with  red-green  and  blue-yellow. 
This  objection  has  been  partly  removed  by  a  further 
development  of  Hering's  theory.1  The  full  explanation  of 
this  relation  lies  undoubtedly  in 
the  proof,  which  W.  Pauli  has 
provided,  that  certain  processes 
ln  colloidal  and  in  living  sub- 
b  stances  can  be  reversed  by  opposite 

processes  along  the  same  path,  or 

"homodromously,"  as  in  A,  while  other  processes  can  only 
be  reversed  by  opposite  processes  along  a  different  path, 
or  "  heterodromously,"  as  in  J2.2  I  myself  shewed  long 
ago  that  certain  sensations  are  related  to  one  another  as 
positive  and  negative  magnitudes  (e.g.,  red  and  green), 
while  others  do  not  stand  in  this  relation  (e.g.,  white  and 
black).3  Now  all  difficulties  are  reconciled  if  we  suppose 

1  Zur  Lehre  vom  Lichtsinne,  Vienna,  1878,  p.  122.  Cp.  also  my 
paper,  previously  cited,  in  the  Sitzungsberichte  der  Wiener  Akademie, 
Vol.  LIL,  1865,  October. 

2W.  Pauli,  Der  Kolliodah  Zustand  und  die  Vorgange  in  der 
lebendigen  Substanz,  Brunswick,  Vieweg,  1902,  pp.  22,  30. 

3  Grundlinicn  der  Lehre  von  den  Bewegungsempfindungen,  1895, 
PP-  57 ,  sqq. 


THE  ANALYSIS  OF  SENSATIONS          69 

with  Pauli  that  the  opposed  processes  as  assumed  by  Hering, 
which  correspond  to  the  first  pair,  are  homodromous,  and 
that  the  processes  underlying  the  second  pair  are  hetero- 
dromous.1 


The  examples  adduced  will  suffice  to  explain  the  signifi- 
cance of  the  above-enunciated  principle  of  inquiry,  and  at 
the  same  time  to  show  that  this  principle  is  not  entirely 
new.  In  formulating  the  principle,  years  ago,  I  had  no 
other  object  than  that  of  making  quite  clear  to  my 
own  mind  a  truth  which  I  had  long  instinctively  felt. 

It  seemed  to  me  a  simple  and  natural,  nay,  an  almost 
self-evident  supposition,  that  similarity  must  be  founded  on 
a  partial  likeness  or  identity,  and  that  consequently,  where 
sensations  were  similar,  we  had  to  look  for  their  common 
identical  constituents  and  for  the  corresponding  common 
physiological  processes.  I  wish,  however,  to  make  it  quite 
clear  to  the  reader  that  this  view  by  no  means  meets  with 
universal  agreement.  We  constantly  find  it  maintained  in 
philosophical  books  that  similarity  may  be  observed  without 
there  being  any  question  at  all  of  such  identical  con- 
stituents. Thus  a  physiologist 2  can  speak  as  follows  of  the 
principle  under  discussion  :  "The  application  of  this  prin- 
ciple to  the  above  problems  leads  him  (Mach)  to  ask.  what 
is  the  physiological  factor  that  corresponds  to  the  qualities 
thus  postulated  ?  Now  it  seems  to  me  that,  of  all  axioms 

1  A  recent  exposition  of  Hering's  views  will  be  found  in  Graefe- 
Saemisch's  Ilandbuck  der  ges.  Aitgenheilkunde,  Leipzig,  1905^ 
Vol.  III. 

2J.  Von  Kries,  Ueber  die  materiellen  Grmidlagen  der  Bewusst- 
seinserscheinu-hgcn^  Freiburg  im  Breisgau,  1898. 


70          THE  ANALYSIS  OF  SENSATIONS 

and  principles,  none  is  more  doubtful,  none  is  exposed  to 
greater  misunderstandings  than  is  this  principle.  If  it  is 
nothing  more  than  a  periphrasis  for  the  so-called  principle 
of  parallelism,  then  it  cannot  be  considered  either  new  or 
particularly  fruitful,  and  it  does  not  deserve  the  importance 
that  is  attached  to  it.  If,  on  the  other  hand,  it  is  intended 
to  mean  that  a  definite  element  or  constituent  of  a 
physiological  event  must  correspond  to  everything  which 
we  can  distinguish  as  having  some  sort  of  psychological 
unity, — to  every  relation,  to  every  form,  in  a  word  to 
everything  that  we  can  denote  by  a  general  concep- 
tion,— then  this  formulation  can  only  be  characterized 
as  dubious  and  misleading."  And  I  am  taken  as 
holding  that  the  principle  in  question  (with  the  re- 
servation made  on  p.  59)  must  be  understood  in  this 
last  "dubious  and  misleading"  sense.  I  must  leave  it 
entirely  to  the  reader  to  choose  whether  he  will 
accompany  me  any  further  and  enter  with  me  on  that 
preliminary  stage  of  inquiry  which  is  clearly  denned  by 
means  of  our  principle,  or  whether,  bowing  to  the  authority 
of  my  opponents,  he  will  turn  back  and  satisfy  himself 
merely  with  considering  the  difficulties  which  confront 
him.  If  he  chooses  the  former  alternative,  he  will, 
I  hope,  discover,  that  when  simpler  cases  have  been 
disposed  of,  the  difficulties  in  cases  of  deeper-lying 
abstract  similarity  no  longer  appear  in  such  a  formidable 
light  as  before.  All  I  will  add  at  present  is,  that  in  these 
more]  complicated  cases  of  similarity  the  similarity  arises 
not  from  the  presence  of  one  common  element,  but  from  a 
common  system  of  elements,  as  I  shall  explain  at  length 
in  connexion  with  conceptual  thinking  (Cf.  Chap.  XIV.). 


THE  ANALYSIS  OF  SENSATIONS          71 

8. 

As  we  recognize  no  real  gulf  between  the  physical  and 
the  psychical,  it  is  a  matter  of  course  that,  in  the  study 
of  the  sense-organs,  general  physical  as  well  as  special 
biological  observations  may  be  employed.  Much  that 
appears  to  us  difficult  of  comprehension  when  we  draw  a 
parallel  between  a  sense-organ  and  a  physical  apparatus, 
is  rendered  quite  obvious  in  the  light  of  the  theory  of 
evolution,  simply  by  assuming  that  we  are  concerned  with 
a  living  organism  with  particular  memories,  particular 
habits  and  manners,  which  owe  their  origin  to  a  long  and 
eventful  race-history.  The  sense-organs  themselves  are  a 
fragment  of  soul ;  they  themselves  do  part  of  the  psychical 
work,  and  hand  over  the  completed  result  to  conscious- 
ness. I  will  here  briefly  put  together  what  I  have  to  say 
on  this  subject. 


The  idea  of  applying  the  theory  of  evolution  to  physio- 
logy in  general,  and  to  the  physiology  of  the  senses  in 
particular,  was  advanced,  prior  to  Darwin,  by  Spencer 
(1855).  It  received  an  immense  impetus  through  Darwin's 
book  The  Expression  of  the  Emotions.  Later,  P.  R. 
Schuster  (1879)  discussed  the  question  whether  there  were 
"  inherited  ideas  "  in  the  Darwinian  sense.  I,  too,  expressed 
myself  in  favor  of  the  application  of  the  idea  of  evolution 
to  the  theory  of  the  sense-organs  (Sitzungsberichte  der 
Wiener  Akademie,  October  1866).  One  of  the  finest 
and  most  instructive  discussions,  in  the  way  of  a  psycho- 
logico-physiological  application  of  the  theory  of  evolution, 


72          THE  ANALYSIS  OF  SENSATIONS 

is  to  be  found  in  the  Academic  Anniversary  Address  of 
Hering,  On  Memory  as  a  General  Function  of  Organized 
Matter ;  1870  (English  translation,  Open  Court  Publishing 
Company,  Chicago,  1913).     As  a  fact,  memory  and  here- 
dity  almost   coincide   in    one   concept   if  we  reflect  that 
organisms,  which  were  part  of  the  parent-body,  emigrate 
and  become   the   basis   of  new  individuals.     Heredity  is 
rendered  almost  as  intelligible  to  us  by  this  thought  as, 
for  example,  is  the  fact  that  Americans  speak  English,  or 
that  their  state-institutions  resemble  the  English  in  many 
respects,    etc.      The   problem   involved   in   the   fact   that 
organisms  possess  memory,  a  property  which  is  apparently 
lacking  to  inorganic  matter,  is,  of  course,  not  affected  by 
these  considerations,  but  still  exists  (cp.  Chapters  V.,  XL). 
If  we  want  to  avoid  criticizing  Hering's  theory  unfairly,  we 
must  observe  that  he  uses  the  conception  of  memory  in  a 
rather  broad  sense.     He  perceived  the  affinity  between  the 
lasting  traces  imprinted  on  organisms  by  their  racial  history, 
and  the  more  evanescent  impressions  which  the  individual 
life  leaves  behind  it  in  consciousness.     He  recognizes  that 
the   spontaneous    reappearance,   in    response   to   a   slight 
stimulus,   of  a   process  which   has   once   been  set  up,   is 
essentially  the   same   event,  whether   it  can  be  observed 
within   the   narrow   framework    of    consciousness   or   not. 
The  perception  of  this  common  feature  in  a  long  series  of 
phenomena  is  an  essential  step  in  advance,  even  though 
this  fundamental  feature  itself  still  remains  unexplained.1 
Recently   Weismann   (Ueber  die  Dauer  des  Lebens,   1882) 
has  conceived  death  as  a  phenomenon  of  heredity.     This 
admirable  book,  also,  has  a  very  stimulating  effect.     The 
1  R.  Semon,  Die  Mneme,  Leipzig,  1904. 


THE  ANALYSIS  OF  SENSATIONS          73 

difficulty  which  might  be  found  in  the  fact  that  a  character- 
istic should  be  inherited  which  can  make  its  appearance  in 
the  parent-organism  only  after  the  process  of  inheritance  is 
ended,  lies  probably  only  in  the  manner  of  statement. 
It  disappears  when  we  consider  that  the  power  of  the 
somatic  cells  to  multiply  can  increase,  as  Weismann  shows, 
at  the  cost  of  the  increase  of  the  germ-cells.  Accordingly, 
we  may  say  that  greater  length  of  life  on  the  part  of  the 
cell-society  and  lessened  propagation  are  two  phenomena 
of  adaptation  which  mutually  condition  each  other. — While 
a  Gymnasium  student,  I  heard  it  stated  that  plants  from 
the  Southern  Hemisphere  bloom  in  our  latitudes,  when  it 
is  spring  in  their  native  place.  I  recall  clearly  the  mental 
shock  which  this  communication  caused  me.  If  it  is  true, 
we  may  actually  say  that  plants  have  a  sort  of  memory, 
even  though  it  be  admitted  that  the  chief  point  involved 
is  the  periodicity  of  the  phenomena  of  life.  The  so-called 
reflex  movements  of  animals  may  be  explained  in  a  natural 
manner  as  phenomena  of  memory  outside  the  organ  of 
consciousness.  I  was  a  witness  of  a  very  remarkable 
phenomenon  of  this  kind — in  1865,  I  think — with  Rollett, 
who  was  experimenting  with  pigeons  whose  brains  had 
been  removed.  These  birds  drink  whenever  their  feet  are 
placed  in  a  cold  liquid,  whether  the  liquid  is  water, 
mercury,  or  sulphuric  acid.  Now  since  a  bird  must 
ordinarily  wet  its  feet  when  it  seeks  to  quench  its  thirst, 
the  view  arises  quite  naturally  that  we  have  here  a  habit 
adapted  to  an  end,  which  is  conditioned  by  the  mode  of 
life  and  fixed  by  inheritance,  and  which,  even  when  con- 
sciousness is  eliminated,  takes  place  with  the  precision  of 
clockwork  on  the  application  of  the  stimulus  appropriate 


74          THE  ANALYSIS  OF  SENSATIONS 

to  its  excitation.  Goltz,  in  his  wonderful  book  Die  Ner- 
vencentren  des  Frosches,  1869,  and  in  later  writings,  has 
described  many  phenomena  of  the  sort. —  I  will  take  this 
opportunity  of  mentioning  some  further  observations  which 
I  recall  with  a  great  deal  of  pleasure.  In  the  autumn 
vacation  of  1873,  mY  nttle  DOV  brought  me  a  sparrow  a 
few  days  old,  which  had  fallen  from  its  nest,  and  wanted 
to  bring  it  up.  But  the  matter  was  not  so  easy.  The 
little  creature  could  not  be  induced  to  swallow,  and  would 
certainly  soon  have  succumbed  to  the  indignities  that 
would  have  been  unavoidable  in  feeding  it  by  force.  I 
then  fell  into  the  following  train  of  thought :  "Whether  or 
not  the  Darwinian  theory  is  correct,  the  new-born  child 
would  certainly  perish  if  it  had  not  the  specially  formed 
organs  and  inherited  impulse  to  suck,  which  are  brought 
into  activity  quite  automatically  and  mechanically  by  the 
appropriate  stimulus.  Something  similar  (in  another  form) 
must  exist  likewise  in  the  case  of  the  bird."  I  exerted 
myself  to  discover  the  appropriate  stimulus.  A  small 
insect  was  stuck  upon  a  sharp  stick  and  swung  rapidly 
about  the  head  of  the  bird.  Immediately  the  bird  opened 
its  bill,  beat  its  wings,  and  eagerly  devoured  the  proffered 
food.  I  had  thus  discovered  the  right  stimulus  for  setting 
the  impulse  and  the  automatic  movement  free.  The 
creature  grew  perceptibly  stronger  and  greedier,  it  began 
to  snatch  at  the  food,  and  once  seized  an  insect  that  had 
accidentally  fallen  from  the  stick  to  the  table ;  from  that 
time  on  it  ate,  without  ceremony,  of  itself.  In  proportion 
as  its  intellect  and  memory  developed,  a  smaller  portion  of 
the  stimulus  was  required.  On  reaching  .independence, 
the  creature  took  on,  little  by  little,  all  the  characteristic 


THE  ANALYSIS  OF  SENSATIONS          75 

ways  of  sparrows,  which  it  certainly  had  not  learnt  by 
itself.  By  day,  with  its  intellect  awake,  it  was  very 
trustful  and  friendly.  In  the  evening,  other  phenomena 
were  regularly  exhibited.  It  grew  timid.  It  always 
sought  out  the  highest  places  in  the  room,  and  would 
become  quiet  only  when  it  was  prevented  by  the  ceiling 
from  going  higher.  Here  again  we  have  an  inherited 
habit  adapted  to  an  end.  On  the  coming  of  darkness, 
its  demeanour  changed  totally.  When  approached,  it 
ruffled  its  feathers,  began  to  hiss,  and  showed  every 
appearance  of  terror  and  real  physical  fear  of  ghosts.  Nor 
is  this  fear  without  its  reasons  and  its  purpose  in  a 
creature  which,  under  normal  circumstances,  may  at  any 
moment  be  devoured  by  some  monster. 

This  last  observation  strengthened  me  in  an  opinion 
already  formed,  that  my  children's  terror  of  ghosts  did 
not  have  its  source  in  nursery  tales,  which  were  carefully 
excluded  from  them,  but  was  innate.  One  of  my  children 
would  regard  with  anxiety  an  arm-chair,  which  stood  in  the 
shadow ;  another  carefully  avoided,  in  the  evening,  a  coal- 
scuttle by  the  stove,  especially  when  this  stood  with  the  lid 
open,  looking  like  gaping  jaws.  The  fear  of  ghosts  is  the 
true  mother  of  religions.  Neither  scientific  analysis  nor 
the  careful  historical  criticism  of  a  David  Strauss,  as  applied 
to  myths,  which,  for  the  strong  intellect,  are  refuted  even 
before  they  are  invented,  will  all  at  once  do  away  with  and 
banish  these  things.  A  motive  which  has  so  long  answered, 
and  in  a  measure  still  answers,  to  actual  economic  needs 
(fear  of  something  worse,  hope  of  something  better),  will 
long  continue  to  exist  in  mysterious  and  uncontrollable  in- 
stinctive trains  of  thought.  Just  as  the  birds  on  uninhabited 


76          THE  ANALYSIS  OF  SENSATIONS 

islands  (according  to  Darwin)  learn  the  fear  of  man  only  after 
the  lapse  of  generations,  so  we  shall  unlearn,  only  after  many 
generations,  that  useless  habit  known  as  the  creeping  of  flesh. 
Every  presentation  of  Faust  may  teach  us  the  extent  to  which 
we  are  still  in  secret  sympathy  with  the  conceptions  of  the 
age  of  witchcraft.  The  exact  knowledge  of  nature  and  of  the 
conditions  of  this  life  gradually  becomes  more  useful  to  man 
than  fear  of  the  unknown.  And  in  time  the  most  impor- 
tant thing  of  all  for  him  is  to  be  on  his  guard  against  his 
fellow-men  who  want  to  oppress  him  violently  or  abuse  him 
treacherously  by  misleading  his  understanding  and  emotions. 
I  will  here  relate  one  other  curious  observation,  for  the 
knowledge  of  which  I  am  indebted  to  my  father  (an 
enthusiastic  Darwinian  and  in  the  latter  part  of  his  life  a 
landed  proprietor  in  Carniola).  My  father  occupied  him- 
self much  with  silk-culture,  raised  the  yama-mai  in  the  open 
oak-woods,  etc.  The  ordinary  mulberry  silkworm  has,  for 
many  generations,  been  raised  indoors,  and  has  consequently 
become  exceedingly  helpless  and  dependent.  When  the 
time  for  passing  into  the  chrysalitic  state  arrives,  it  is  the 
custom  to  give  the  creatures  bundles  of  straw,  upon  which 
they  spin  their  cocoons.  Now  it  one  day  occurred  to  my 
father  not  to  prepare  the  usual  bundles  of  straw  for  a 
colony  of  silk-worms.  The  result  was  that  the  majority  of 
the  worms  perished,  and  only  a  small  portion,  the  geniuses 
(those  with  the  greatest  power  of  adaptation)  spun  their 
cocoons.  Whether,  as  my  sister  believes  she  has  observed, 
the  experiences  of  one  generation  are  utilized,  in  noticeable 
degree,  in  the  very  next  generation,  is  a  question  which 
probably  requires  to  be  left  to  further  investigation.  The 
experiments  made  by  C.  Lloyd  Morgan  (Comparative 


THE  ANALYSIS  OF  SENSATIONS          77 

Psychology,  London,  1894)  with  young  chickens,  ducks, 
etc.,  shew  that,  at  any  rate  in  the  case  of  the  higher  animals, 
scarcely  anything  is  innate  but  the  reflexes.  The  newly- 
hatched  chick  at  once  begins  to  peck  with  great  assurance 
at  everything  that  it  sees ;  but  it  has  to  learn  what  is  suit- 
able to  pick  up  by  its  individual  experience.  The  simpler 
the  organism,  the  smaller  the  part  played  by  individual 
memory.  From  all  these  remarkable  phenomena  we  need 
derive  no  mysticism  of  the  Unconscious.  A  memory 
reaching  beyond  the  individual  (in  the  broader  sense 
defined  above)  renders  them  intelligible. — A  psychology  in 
the  Spencer-Darwinian  sense,  founded  upon  the  theory  of 
evolution,  but  supported  by  detailed  positive  investigation, 
would  yield  richer  results  than  all  previous  speculation  has 
done. — These  observations  and  reflections  had  long  been 
made  and  written  down  when  Schneider's  valuable  work, 
Der  thierische  Wille,  Leipzig,  1880,  which  contains  many 
that  are  similar,  made  its  appearance.  I  agree  with  the 
details  of  Schneider's  discussions  (in  so  far  as  they  have 
not  been  made  problematical  by  Lloyd  Morgan's  experi- 
ments) almost  throughout,  although  his  fundamental  con- 
ceptions in  the  realms  of  natural  science  with  regard  to 
the  relation  of  sensation  and  physical  process,  the  signifi- 
cance of  the  survival  of  species,  etc.,  are  essentially  different 
from  mine,  and  although  I  hold,  for  instance,  the  distinction 
between  sensation-impulses  and  perception-impulses  to  be 
quite  superfluous. — An  important  revolution  in  our  views 
on  heredity  may  perhaps  be  produced  by  Weismann's  work, 
Ueber  die  Vererbung,  Jena,  1883  (English  translation,  Essays 
on  Heredity  and  Kindred  Biological  Problems,  Oxford,  The 
Clarendon  Press,  1889).  Weismann  regards  the  inheritance 


78          THE  ANALYSIS  OF  SENSATIONS 

of  traits  acquired  by  use  as  highly  improbable,  and  finds  in 
chance  variation  of  the  germ-elements  and  in  the  selection 
of  the  germ-elements  the  most  important  factors.  Whatever 
attitude  we  adopt  towards  Weismann's  theories,  the  dis 
cussion  initiated  by  him  must  contribute  to  the  elucidation 
of  these  questions.  No  one  will  refuse  to  recognize  the 
almost  mathematical  acuteness  and  depth  of  the  way  in 
which  he  states  the  problem,  and  it  cannot  be  denied  that 
his  arguments  have  much  force.  He  makes,  for  instance, 
the  extremely  suggestive  remark  that  it  is  impossible  that 
the  peculiar  and  unusual  forms  of  sexless  ants,  which  must 
apparently  be  referred  to  use  and  adaptation,  and  which 
moreover  deviate  so  remarkably  from  the  forms  of  ants 
that  are  capable  of  propagation,  should  be  produced  by 
inheritance  of  characteristics  acquired  by  use.1  That  the 
germ-elements  themselves  may  be  altered  by  external  in- 
fluences appears  to  be  clearly  shewn  by  the  formation 
of  new  races,  which  maintain  themselves  as  such,  trans- 
mit their  racial  traits  by  inheritance,  and  are  themselves, 
again,  capable  of  transformation,  under  other  circum- 
stances. Accordingly,  some  influence  must  certainly  be 
exerted  on  the  germ-plasm  by  the  body  which  envelops  it 
(as  Weismann  himself  admits).  Thus  an  influence  of  the 
individual  life  upon  its  descendents  can  certainly  not  be 
entirely  excluded,  even  although  a  direct  transmission  to 
the  descendents  of  the  results  of  use  in  the  individual  can 
(according  to  Weismann)  no  longer  be  expected.  In 
entertaining  the  notion  that  the  germ-elements  vary  acci- 

1  But  perhaps  the  powerful  mandibles  of  the  sexless  ants  are  the 
original  acquisition  of  the  species,  and  merely  appear  in  an  atrophied 
form  in  the  individuals  to  whom  propagation  of  the  race  is  confined. 


THE  ANALYSIS  OF  SENSATIONS          79 

dentally,  we  must  bear  in  mind  that  chance  is  not  a  principle 
of  action.  When  periodic  circumstances  of  different  kinds 
and  different  periodicities  coincide  in  accordance  with 
definite  causal  laws,  the  circumstances  overlap  in  such  a 
way  that  in  any  particular  case  it  is  impossible  to  see  that 
any  law  is  involved.  But  the  law  reveals  itself  with  the 
lapse  of  a  long  enough  time,  and  permits  us  to  calculate  on 
certain  average  values  or  probabilities  of  effects.1  Without 
some  such  principle  of  action,  chance  or  probability  is 
meaningless.  And  what  principle  of  action  can  be  con- 
ceived as  exercising  more  influence  on  the  variation  of  the 
germ-elements  than  the  body  of  the  parent  ?  Personally  I 
cannot  understand  how  it  is  possible  that  the  species  should 
succumb  to  the  influence  of  varying  circumstances,  and  yet 
that  these  circumstances  should  not  affect  the  individual. 
Moreover,  I  am  certain  that  I  myself  vary  with  every 
thought,  every  memory,  every  experience ;  all  these  factors 
undoubtedly  change  my  whole  physical  behaviour.2 

Although  it  is  scarcely  necessary,  I  should  like  to  add 
explicitly  that  I  regard  the  theory  of  evolution,  in  whatever 
form,  as  a  working  scientific  hypothesis,  capable  of  being 
modified  and  of  being  made  more  precise,  which  is  valuable 
in  so  far  as  it  facilitates  the  provisional  understanding  of 
what  is  given  in  experience.  I  have  been  a  witness  of  the 
powerful  impetus  which  Darwin's  work  gave  in  my  time 
not  merely  to  biology,  but  to  all  scientific  enquiry,  and  it 
is  not  likely  that  I  should  underestimate  the  value  of  the 
theory  of  evolution.  But  I  would  not  quarrel  with  anyone 

1  Vorlesungen  ilber  Psychophysik,  Zeitschrift  fur  prakt.  Heilkunde, 
pp.  148,  168,  169,  Vienna,  1863. 

2  Popular  Scientific  Lectures,  Chicago,  Open  Court  Publishing  Co. 


8o          THE  ANALYSIS  OF  SENSATIONS 

who  should  rate  its  value  very  low.  As  long  ago  as  1883 
and  1886  I  dwelt  on  the  necessity  of  advancing  by  means 
of  more  precise  conceptions  obtained  by  the  study  of 
biological  facts  for  their  own  sakes.1  Thus  I  am  by  no 
means  committed  to  a  refusal  to  understand  investigations 
such  as  those  of  Driesch.  But  whether  Driesch's  criticism 
of  my  attitude  towards  the  theory  of  evolution  is  justified,2 
I  leave  to  anyone  to  decide  who,  even  after  this  criticism, 
still  cares  to  be  at  the  pains  of  reading  my  works. 


10. 

Teleological  conceptions,  as  aids  to  investigation,  are  not 
to  be  shunned.  It  is  true,  our  comprehension  of  the  facts 
of  reality  is  not  enhanced  by  referring  them  to  an  unknown 
World-Purpose,  itself  problematical,  or  to  the  equally 
problematical  purpose  of  a  living  being.  Nevertheless, 
the  question  as  to  the  value  that  a  given  function  has  for 
the  existence  of  an  organism,  or  as  to  what  are  its  actual 
contributions  to  the  preservation  of  the  organism,  may  be 
of  great  assistance  in  the  comprehension  of  this  function 
itself.3  Of  course  we  must  not  suppose,  on  this  account, 

1  Cp.  Popular  Scientific  Lectures,  and  Analyse  der  Empfindungen^ 
1886,  pp.  34,  sqq. 

2 Driesch,  Die  organisatorischen  Regulationen,  pp.  165,  sqq.,  1901. 

3  Such  teleological  conceptions  have  often  been  useful  and  instructive 
to  me.  The  remark,  for  example,  that  a  visible  object  under  varying 
intensity  of  illumination  can  be  recognized  as  the  same  only  when  the 
sensation  excited  depends  on  the  ratio  of  the  illumination-intensities  of 
object  and  surroundings,  makes  intelligible  a  whole  train  of  organic 
properties  of  the  eye.  (Cp.  Hering  in  Graefe-Saemisch's  Handbrich  der 
Augenheilkunde,  Vol.  III.,  Ch.  12,  pp.  13,  sqq.)  In  this  way  we  under- 
stand also,  how  the  organism,  in  the  interest  of  its  survival,  was  obliged 


THE  ANALYSIS  OF  SENSATIONS          81 

as  many  Darwinians  have  done,  that  we  have  "  mechanically 
explained  "  a  function,  when  we  discover  that  it  is  necessary 
for  the  survival  of  the  species.  Darwin  himself  is  doubt- 
less quite  free  from  this  short-sighted  conception.  By 
what  physical  means  a  function  is  developed,  still  remains 
a  physical  problem  ;  while  the  how  and  why  of  an  organism's 
voluntary  adaptation  continues  to  be  a  psychological  pro- 
blem. The  preservation  of  the  species  is  only  one,  though 
an  actual  and  very  valuable,  point  of  departure  for  inquiry, 
but  it  is  by  no  means  the  last  and  the  highest.  Species 

to  adjust  itself  to  the  requirement  mentioned  and  to  adapt  itself  to  feel 
the  ratios  of  light-intensity.  The  so-called  law  of  Weber,  or  the  funda- 
mental psycho-physical  formula  of  Fechner,  thus  appears  not  as  some- 
thing fundamental,  but  as  the  explicable  result  of  organic  adjustments. 
The  belief  in  the  universal  validity  of  this  law  is,  naturally,  herewith 
relinquished.  I  have  given  the  arguments  on  this  point  in  various 
papers.  (Sitzungsberichte  der  Wiener  Akademie,  Vol.  LI  I.,  1865  ; 
Vierteljahrsschrijt  fur  Psychiatric^  Neuwied  and  Leipzig,  1868; 
Sitzimgsberichte  der  Wiener  Akademie,  Vol.  LVIL,  1868).  In  the 
last-named  paper,  proceeding  from  the  postulate  of  the  parallelism 
between  the  psychical  and  the  physical,  or,  as  I  then  expressed  myself, 
from  the  proportionality  between  stimulus  and  sensation,  I  abandoned 
the  metrical  formula  of  Fechner  (the  logarithmic  law),  and  brought 
forward  another  conception  of  the  fundamental  formula,  the  validity  of 
which  for  light-sensation  I  never  disputed.  This  is  apparent  beyond 
all  doubt  from  the  way  in  which  that  paper  is  worked  out.  Thus  one 
cannot  say,  as  Hering  has  done,  that  I  everywhere  take  the  psycho- 
physical  law  as  my  foundation,  if  by  this  is  understood  the  metrical 
formula.  How  could  I  have  maintained  the  proportionality  between 
stimulus  and  sensation  at  the  same  time  with  the  logarithmic  depend- 
ence? It  was  sufficient  for  me  to  render  my  meaning  clear; — to 
criticize  and  contest  Fechner's  law  in  detail,  I  had,  for  many  obvious 
reasons,  no  need.  Strictly  speaking  I  consider  the  expression  "pro- 
portionality "  also  to  be  inappropriate,  since  there  can  be  no  question 
of  an  actual  measurement  of  the  sensations  ;  all  that  can  be  done  is  to 
characterize  them  exactly  and  make  an  inventory  of  them  by  numerical 
means.  Cp.  what  I  have  said  about  the  characterization  of  states  of 
heat  (Prinzipien  der  Warmelehre,  p.  56). 
F 


82          THE  ANALYSIS  OF  SENSATIONS 

have  certainly  been  destroyed,  and  new  ones  have  as 
certainly  arisen.  The  pleasure-seeking  and  pain-avoiding 
will,1  therefore,  is  directed  perforce  beyond  the  preservation 
of  the  species.  It  preserves  the  species  when  it  is  advan- 
tageous to  do  so,  and  destroys  it  when  its  survival  is  no 
longer  advantageous.  Were  it  directed  merely  to  the 
preservation  of  the  species,  it  would  move  aimlessly  about 
in  a  vicious  circle,  deceiving  both  itself  and  all  individuals. 
This  would  be  the  biological  counterpart  of  the  notorious 
"perpetual  motion"  of  physics.  The  same  absurdity  is 
committed  by  the  statesman  who  regards  the  state  as  an 
end  in  itself. 

1  Schopenhauer's  conception  of  the  relation  between  Will  and  Force 
can  quite  well  be  adopted  without  seeing  anything  metaphysical  in 
either. 


V.  PHYSICS  AND  BIOLOGY. 
CAUSALITY  AND  TELEOLOGY. 


IT  often  happens  that  the  development  of  two  different 
fields  of  science  goes  on  side  by  side  for  long 
periods,  without  either  of  them  exercising  an  influence  on 
the  other.  On  occasion,  again,  they  may  come  into  closer 
contact,  when  it  is  noticed  that  unexpected  light  is  thrown 
on  the  doctrines  of  the  one  by  the  doctrines  of  the  other. 
In  that  case  a  natural  tendency  may  even  be  manifested 
to  allow  the  first  field  to  be  completely  absorbed  in  the 
second.1  But  the  period  of  buoyant  hope,  the  period  of 
over-estimation  of  this  relation  which  is  supposed  to 
explain  everything,  is  quickly  followed  by  a  period  of 
disillusionment,  when  the  two  fields  in  question  are  once 
more  separated,  and  each  pursues  its  own  aims,  putting 
its  own  special  questions  and  applying  its  own  peculiar 
methods.  But  on  both  of  them  the  temporary  contact 
leaves  abiding  traces  behind.  Apart  from  the  positive 
addition  to  knowledge,  which  is  not  to  be  despised,  the 
temporary  relation  between  them  brings  about  a  trans- 
formation of  our  conceptions,  clarifying  them  and  permitting 
of  their  application  over  a  wider  field  than  that  for  which 
they  were  originally  formed. 

1  Cp.  W.  Pauli,  Physikalische-chemische  Methods*  in  der  Medizin^ 
Vienna,  1900,  where  an  allied,  but  more  narrowly  limited,  question 
is  dealt  with. 

83 


84          THE  ANALYSIS 'OF  SENSATIONS 


2. 


We  are  living  at  present  in  such  a  period  of  complicated 
cross-relations,  and  the  consequent  fermentation  of  ideas 
gives  rise  to  very  remarkable  phenomena.  While  many 
physicists  are  concerned  to  purify  physical  conceptions  by 
psychological,  logical  and  mathematical  methods,  other 
physicists,  mistrustful  of  this  tendency,  and  more  philo- 
sophical than  the  philosophers  themselves,  are  coming 
forward  as  advocates  of  the  old  metaphysical  conceptions 
which  the  philosophers  have  already  largely  abandoned. 
Philosophers,  psychologists,  biologists,  and  chemists,  all 
make  the  most  widely  extended  applications  of  the  principle 
of  energy  and  of  other  physical  conceptions,  with  a  freedom 
which  the  physicist  would  hardly  venture  to  use  in  his 
own  field.  We  may  almost  say  that  the  customary  roles 
of  the  special  departments  have  been  interchanged.  The 
success  of  this  movement  may  be  partly  positive  and 
partly  negative,  but  in  any  case  the  result  of  it  will  be  a 
more  precise  determination  of  our  conceptions,  a  more 
accurate  delimitation  of  the  sphere  to  which  they  apply, 
and  a  clearer  idea  of  the  difference  and  the  affinity  between 
the  methods  of  the  departments  in  question. 


We  are  here  concerned  in  particular  with  the  relations 
between  the  physical  and  biological  fields  in  the  broadest 
sense.  The  distinction  between  effective  causes  and  final 
causes,  or  ends,  dates  from  Aristotle.  It  has  been 
generally  assumed  that  physical  phenomena  are  throughout 


THE  ANALYSIS  OF  SENSATIONS          85 

determined  by  effective  causes,  and  biological  phenomena 
by  final  causes.  The  acceleration  of  a  body,  for  example, 
is  determined  solely  by  the  effective  causes, — by  the 
circumstances  of  the  movement,  such  as  the  presence  of 
other  gravitating  magnetic  or  electrical  bodies.  Up  to  the 
present  we  are  not  able  to  deduce  the  development  of  a 
growing  animal,  or  the  development  of  a  plant  in  its  peculiar 
determinate  forms,  or  the  instinctive  actions  of  an  animal, 
from  effective  causes  alone  ;  but  such  facts  as  these  can 
be  at  any  rate  partially  understood  when  we  take  into 
consideration  the  purpose  of  self-preservation  under  the 
particular  circumstances  of  the  organism's  life.  Whatever 
theoretical  reservations  we  may  make  as  to  the  application 
to  biology  of  the  conception  of  purpose,  it  would  certainly 
be  perverse,  in  a  field  where  the  "causality"  theory  still 
affords  such  imperfect  explanations,  to  refuse  to  make  use 
of  the  clues  which  a  consideration  of  purpose  puts  into  our 
hands.  I  do  not  know  what  it  is  that  compels  the  cater- 
pillar of  the  hawk-moth  to  spin  a  cocoon  with  a  bristly 
flap  opening  outwards,  but  I  see  that  such  a  cocoon  exactly 
corresponds  to  the  purpose  of  preserving  the  caterpillar's 
existence.  I  am  far  from  being  able  to  understand 
"  causally  "  the  numerous  remarkable  phenomena,  described 
and  studied  by  Reimarus  and  Autenrieth,  of  the  develop- 
ment and  instinctive  action  of  animals  ;  but  I  understand 
them  in  the  light  of  the  purpose  of  preserving  the  animal's 
existence  in  the  particular  conditions  of  life  involved. 
These  phenomena  consequently  merit  attention ;  they 
become  fused  in  the  picture  which  we  form  of  the  life  of 
the  organism  as  ineffaceable  constituents ;  and  it  is  only 
through  them  that  that  picture  can  be  rounded  out  into  a 


86          THE  ANALYSIS  OF  SENSATIONS 

united  and  connected  whole.  But  it  is  only  quite  recently, 
— and  particularly  through  the  investigations  of  Sachs  in 
the  physiology  of  plants  and,  in  animal  physiology,  through 
the  work  of  Loeb  on  geotropism,  heliotropism,  stereo- 
tropism,  etc., — that  the  relations  between  growth  and 
instinct  have  been  really  explained  in  such  a  way  that  we 
can  begin  to  conceive  these  relations  also  as  "causal." 
History  testifies  in  a  manner  that  cannot  be  gainsaid  to 
the  utility  of  the  conception  of  purpose  in  biological 
research.  Consider  only  Kepler's  investigation  of  the 
eye.  It  was  impossible  for  him,  in  view  of  the  purpose  of 
the  eye,  namely  clear  vision  at  different  distances,  to  doubt 
the  existence  of  accommodation;  but  it  was  not  until  150 
years  later  that  the  processes  which  effect  the  accommo- 
dation were  really  discovered.  Harvey  discovered  the 
circulation  of  the  blood  in  the  course  of  an  attempt  to 
make  clear  to  himself  the  problematical  purpose  of  the 
position  of  the  valves  of  the  heart  and  veins. 

Even  when  a  department  of  facts  has  been  completely 
explained  teleologically,  the  need  to  understand  it  "  causally  " 
still  persists.  The  belief  in  the  completely  different  nature 
of  the  two  departments  we  are  considering,  in  virtue  of 
which  one  is  to  be  understood  only  in  a  causal  sense  and 
the  other  only  in  a  teleological  sense,  is  not  justified.  A 
complex  of  physical  facts  is  something  simple,  or  at  any 
rate  in  many  cases  can,  at  will,  be  experimentally  represented 
in  such  a  simple  form  that  the  immediate  relations  between 
its  parts  become  visible.  Now  supposing  that  we  have 
done  sufficient  work  in  this  department  to  have  enabled  us 
to  acquire,  as  regards  the  nature  of  these  relations,  con- 
ceptions which  we  think  correspond  to  the  facts  universally, 


THE  ANALYSIS  OF  SENSATIONS          87 

then  we  are  logically  bound  to  expect  that  any  particular 
fact  which  may  present  itself  will  correspond  to  these  con- 
ceptions. But  this  implies  no  necessity  in  nature.1  It  is  in 
this  that  "  causal "  understanding  consists.  A  biological 
factual  complex,  on  the  other  hand,  is  compounded  in  such 
a  way  that  the  immediate  relations  between  its  parts  cannot 
be  taken  in  at  a  glance.  Accordingly  we  are  satisfied  if  we 
are  able  to  represent  as  being  connected  with  one  another 
prominent  parts  of  the  complex  which  are  not  immediately 
connected.  But  the  intellect  which  has  been  trained  to 
familiarity  with  the  simpler  causal  relation  finds,  in  the 
absence  of  the  intermediate  links,  difficulties  which  it  tries 
to  remove  as  best  it  can, — either  by  trying  to  discover  these 
iniermediate  links,  or  by  grasping  at  the  hypothesis  of  a 
quite  new  kind  of  connecting  relations.  The  latter  alter- 
native is  unnecessary,  if  we  regard  our  knowledge  as 
imperfect  and  provisional,  and  reflect  that  in  the  department 
of  physics  absolutely  analogous  cases  arise.  The  scientists 
of  antiquity,  indeed,  did  not  draw  this  precise  distinction 
between  the  two  departments.  Aristotle,  for  example,  con- 
ceives heavy  bodies  as  seeking  out  their  position;  Hero 
thinks  that,  from  motives  of  economy,  nature  conducts  light 
by  the  shortest  paths  and  in  the  shortest  times.  These 
inquirers  thus  set  up  no  such  definite  boundary  between 
the  physical  and  the  biological.  Moreover,  by  an  imper- 
ceptible modification  in  our  thought,  we  can  formulate 
every  teleological  question  in  such  a  way  as  completely  to 
exclude  the  conception  of  purpose.  The  eye  sees  clearly 
at  different  distances ;  the  apparatus  of  dioptrical  vision 

1  Prinzipien  der   Wcirmelehre,  2nd  edition,  Leipzig,  1900,  pp.  434, 
457- 


88          THE  ANALYSIS  OF  SENSATIONS 

must  therefore  be  capable  of  change ;  in  what  does  this 
change  consist?  The  valves  of  the  heart  and  veins  all 
open  in  the  same  direction  ;  this  being  so,  the  circulation 
of  the  blood  can  only  take  place  in  one  direction.  Is  this 
the  fact  ?  The  modern  theory  of  evolution  has  made  this 
sober  method  of  thought  its  own.  Even  in  the  very  ad- 
vanced parts  of  physics,  on  the  other  hand,  we  come  across 
considerations  having  a  great  affinity  with  those  of  the 
biological  sciences.  The  investigation,  for  example,  of  the 
possibility,  under  certain  conditions,  of  stationary  vibrations 
(i.e.,  vibrations  which  can  maintain  themselves)  has  for  some 
time  past  been  in  an  advanced  state.  It  is  only  quite 
recent  work,  however,  which  has  made  clear  the  manner  in 
which  they  arise.1  We  explain  the  movement  of  light  along 
the  shortest  paths  by  means  of  a  selection  of  the  affective 
paths.  At  present  the  conceptions  used  by  chemists  are 
even  closer  to  those  of  the  biologist.  According  to  these 
conceptions  all  possible  combinations  are  formed  by  the 
resolution  of  elements ;  but  combinations  which  cannot  be 
resolved,  and  have  greater  power  of  resistance  to  new  attacks, 
get  the  better  of  the  others  and  survive.  It  thus  would 
appear  that  there  is  as  yet  no  necessity  to  assume  a  funda- 
mental difference  between  teleological  and  causal  methods 
of  investigation.  The  former  is  simply  a  provisional 
method. 

5- 
To  confirm  this  conclusion  in  greater  detail,  let  us  return 

1  Cp.  W.  C.  L.  van  Schaik,  Ueber  die  Tonerregung  in  Labialpfeifen. 
Rotterdam,  1891 ;  V.  Hensen,  Annalen  der  Physik,  4th  Series,  Vol. 
III.,  p.  719,  1900. 


THE  ANALYSIS  OF  SENSATIONS          89 

to  the  various  conceptions  of  causality.  The  old  traditional 
conception  of  causality  is  of  something  perfectly  rigid  :  a 
dose  of  effect  follows  on  a  dose  of  cause.  A  sort  of 
primitive,  pharmaceutical  conception  of  the  universe  is  ex- 
pressed in  this  view,  as  in  the  doctrine  of  the  four  elements. 
The  very  word  "  cause  "  makes  this  clear.  The  connections 
of  nature  are  seldom  so  simple,  that  in  any  given  case  we 
can  point  to  one  cause  and  one  effect.  I  therefore  long  ago 
proposed  to  replace  the  conception  of  cause  by  the  mathe- 
matical conception  of  function, — that  is  to  say,  by  the  con- 
ception of  the  dependence  of  phenomena  on  one  another, 
or,  more  accurately,  the  dependence  of  the  characteristics  of 
phenomena  on  one  another.1  This  conception  is  capable 
of  any  extension  or  limitation  that  may  be  desired,  accord- 
ing to  what  is  required  by  the  facts  under  investigation. 

Perhaps,  therefore,  great  importance  need  not  be  attached 
to  the  objections  that  have  been  raised  against  it.2  Consider, 
as  a  simple  example,  the  relation  of  gravitating  masses.  If 
a  mass  B  comes  into  opposition  to  a  mass  A,  a  movement 
of  A  towards  B  follows.  This  is  the  old  formula.  But,  if 

1  Die  Geschichte  und  die  Wurzel  des  Satzes  der  Erhaltung  der  Arbeit, 
Prague,  Calve,  1872.    (English  translation,  History  and  Root  of  the 
Principle  of  the    Conservation   of  Energy,    by   P.    E     B.   Jourdain, 
Chicago,  Open  Court  Publishing  Co.,  1911.) 

2  Such   objections   have    been   raised  by  Kiilpe   in   his    Ueber  die 
Beziehungen  zwischen  kbrperlichen  und  seelischen  Vorgdngen  (Zeitschrift 

fur  Hypnotismus,  Vol.  VII.,  p.  97),  also  by  Cossman  in  his  Empirische 
Teleologie,  Stuttgart,  1899,  p.  22.  I  do  not  think  that  my  view  differs 
so  greatly  from  Cossman's  that  an  understanding  is  impossible.  If  he 
had  considered  the  matter  further,  he  would  have  seen  that  I  substituted 
the  notion  of  function  for  the  old  notion  of  causality,  and  that  the 
notion  of  function  is  sufficient  also  for  those  cases  which  he  has  in  view. 
I  have  no  further  objection  to  make  to  his  "  Empirical  teleology."  Cp. 
also  C.  Ilauptmann  Die  Metaphysik  in  der  Physiologic,  Dresden,  1893. 


go          THE  ANALYSIS  OF  SENSATIONS 

we  consider  the  matter  more  accurately,  we  see  that  the 
masses  A  B  C  D.  .  .  determine  mutual  accelerations  in 
one  another,  accelerations  which,  therefore,  are  given  as 
soon  as  the  masses  are  posited.  The  accelerations  allow  us 
to  infer  the  velocities  which  will  be  attained  at  some  future 
moment.  Hence  also  the  positions  of  A  B  C  D.  .  .  are 
determined  for  every  moment.  But  the  physical  measure- 
ment of  time  is  based  in  its  turn  upon  a  measurement  of 
space,  namely  the  rotation  of  the  earth.  We  are  thus  ulti- 
mately left  with  a  mutual  dependence  of  positions  on  one 
another.  Thus,  even  in  this  simplest  case,  the  old  formula 
is  incapable  of  embracing  the  multiplicity  of  the  relations 
that  exist  in  nature.  Similarly  in  other  cases  everything  is 
resolved  into  relations  of  mutual  dependence,1  as  to  the 
form  of  which  nothing  of  course  can  be  said  beforehand, 
since  this  is  a  question  which  can  only  be  settled  by  special- 
ized inquiry.  With  a  relation  of  mutual  dependence  change 
is  only  possible  when  some  group  of  the  related  elements 
can  be  regarded  as  an  independent  variable.  Consequently, 
though  it  may  be  possible  to  complete  in  detail  the  picture 
of  the  world  in  a  scientifically  determined  manner  when  a 
sufficient  part  of  the  world  is  given,  yet  science  cannot  tell 
us  what  the  total  result  of  the  world  process  will  be. 

Given  a  well-defined  mechanical  system  (defined,  say, 
by  central  forces),  with  its  positions  and  velocities,  its  con- 
figuration is  determined  as  a  function  of  time.  We  know 
its  configuration  for  any  time  we  like  before  and  after  the 
time  of  commencement,  and  can  thus  prophesy  both  back- 
wards and  forwards.  This  can  only  happen  in  both  cases 
when  no  disturbance  intervenes  from  outside,  when,  that  is 
1  Cp.  Erkenntnis  und  Irrttim  (1905),  p.  274. 


THE  ANALYSIS  OF  SENSATIONS          91 

to  say,  the  system  can  be  regarded  as  in  a  certain  sense  a 
closed  system.  We  cannot,  indeed,  regard  any  system  as 
being  completely  isolated  from  the  rest  of  the  world,  inas- 
much as  the  determination  of  time,  and  consequently  also 
that  of  the  velocities,  presupposes  dependence  on  a  para- 
meter which  is  determined  by  the  path  traversed  by  some 
body,  such  as  a  planet,  lying  outside  the  system.  The 
actual  dependence,  even  though  it  be  not  an  immediate 
dependence  of  all  processes  on  the  position  of  one  body, 
guarantees  to  us  the  interconnection  of  the  whole  world. 
Analogous  considerations  hold  for  any  physical  system, 


Fig.  i  b. 

even  when  it  is  not  conceived  as  a  mechanical  system  also. 
All  accurately  and  clearly  recognized  relations  may  be  re- 
garded as  mutual  relations  of  simultaneity. 

Let  us  consider,  by  way  of  contrast,  the  popular  concep- 
tion of  cause  and  effect.  Let  5  in  Fig.  i,  b,  represent  the  sun, 
which  illumines  a  body  ^placed  in  any  medium  whatever. 
Then  the  sun,  or  the  heat  of  the  sun,  is  the  cause  of  a  rise 
in  temperature  in  the  body  K.  The  rise  follows  regularly 
on  the  illumination  of  K.  On  the  other  hand,  the  body 
K)  or  the  change  in  its  temperature,  cannot  be  regarded 
as  the  cause  of  the  change  in  the  sun's  temperature,  as 
would  actually  be  the  case  if  S  and  K  stood  alone  in  an 
immediate  relation  to  one  another.  The  two  changes 
would  then  be  simultaneous,  and  would  mutually  determine 
one  another.  The  reason  that  this  is  not  so  is  to  be  sought 


92          THE  ANALYSIS  OF  SENSATIONS 

in  the  intermediate  links,  the  elements,  A  B,  of  the 
medium,  which  determine  changes  not  only  in  K^  but  also 
in  other  elements,  and  in  their  turn  are  determined  by 
these  latter.  Thus  K  stands  in  relations  of  mutual  deter- 
mination with  innumerable  elements,  and  only  a  vanishing 
portion  of  the  light  it  reflects  finds  its  way  back  to  the 
sun.  It  is  in  analogous  circumstances  that  we  must 
look  for  the  reason  why  a  body  K  throws  an  image  upon 
the  retina  N^  and  sets  up  a  visual  sensation  E,  from  which 
a  memory  remains  behind,  although  the  memory  does  not 
restore  either  the  retina  N  or  the  whole  body  K.  The 
principal  advantage  for  me  of  the  notion  of  function  over 
that  of  cause  lies  in  the  fact  that  the  former  forces  us  to 
greater  accuracy  of  expression,  and  that  it  is  free  from  the 
incompleteness,  indefmiteness  and  one-sidedness  of  the. 
latter.  The  notion  of  cause  is,  in  fact,  a  primitive  and 
provisional  way  out  of  a  difficulty.  Every  modern  man  of 
science  must,  I  think,  feel  this,  when,  for  instance,  he 
glances  at  J.  S.  Mill's  discussion  of  the  methods  of  experi- 
mental inquiry.  If  he  were  to  try  to  apply  these  methods 
he  would  never  get  beyond  the  most  rudimentary  results. 
The  range  of  spatial  and  temporal  functional  relations 
within  which  our  conjectures  operate,  may  be  one  of  which 
the  limits  lie  very  far  apart :  starting  from  the  present  we  may 
try  to  prophesy  into  the  distant  future  or  past,  and  we  may 
make  fortunate  guesses.  But,  the  greater  the  distance,  the 
less  secure  must  the  basis  of  our  reasoning  be.  It  is  there- 
fore, without  prejudice  to  the  greatness  of  Newton's  concep- 
tion of  action  at  a  distance,  a  very  important  step  in  advance 
that  modern  physics,  wherever  it  can,  requires  that  due  con- 
sideration should  be  paid  to  spatial  and  temporal  continuity. 


THE  ANALYSIS  OF  SENSATIONS          93 


6. 

It  might  seem  from  what  has  been  said  that,  both  in 
physics  and  biology,  the  notion  of  function  was  all  that  we 
wanted,  and  that  this  notion  would  prove  equal  to  all 
requirements.  We  need  not  be  alarmed  by  the  great 
difference  in  point  of  view  displayed  by  the  two  sciences. 
Quite  closely  related  groups  of  physical  phenomena,  as  for 
example  frictional  electricity  and  galvanic  electricity,  look 
so  different  that  at  first  sight  it  might  seem  impossible  to 
expect  that  the  two  should  be  capable  of  reduction  to  the 
same  fundamental  facts.  The  magnetic  and  chemical 
phenomena,  which  are  scarcely  observable  in  the  case  of 
frictional  electricity,  and  could  only  with  difficulty  have  been 
discovered  there  at  all,  are  extremely  prominent  in  galvanic 
electricity  ;  whereas,  contrariwise,  it  is  only  in  the  case  of  the 
former  that  ponderomotive  phenomena  and  phenomena  of 
tension  present  themselves  easily  and  unsought  for.  Now 
it  is  well  known  that  each  of  these  two  studies  supplements 
and  throws  great  light  on  the  other ;  so  much  so  that  we 
have  reached  the  point  of  discovering  the  chemical  nature 
of  frictional  electricity  by  means  of  galvanic  electricity. 

An  analogous  relation  also  holds  between  physics  and 
biology.  Both  contain  the  same  fundamental  facts;  but 
many  sides  of  these  facts  come  to  light  only  in  one  of 
them,  while  many  other  sides  are  only  noticeable  in  the 
other,  so  that  physics,  standing  side  by  side  with  biology, 
can  afford  help  to  and  throw  light  upon  biology,  and  vice 
versa.  No  one  can  deny  that  the  application  of  physics 
to  biology  has  accomplished  much ;  but  against  these 


94          THE  ANALYSIS  OF  SENSATIONS 

achievements  we  have  to  set  other  cases  in  which  it  was 
reserved  for  biology  to  bring  to  light  new  physical  facts 
(galvanism,  PfefTer's  cells,  etc.).  Physics  will  accomplish 
much  more  in  biology,  if  only  she  will  submit  to  have 
additions  made  to  her  by  the  latter. 


If  anyone  familiar  with  the  physical  sciences  alone  were 
to  turn  to  the  study  of  biology,  and  thereupon  were  to 
suppose  that  an  animal  grows  special  organs  which  it  finds 
ready  to  be  applied  to  some  useful  purpose  at  a  later  stage 
of  its  life,  or  that  it  can  perform  instinctive  actions  which  it 
cannot  have  learnt  and  which  can  only  inure  to  the  advan- 
tage of  future  members  of  the  race,  or  that  it  adapts  its 
coloration  to  its  environment  in  order  to  avoid  possible 
future  enemies, — on  such  suppositions  he  would  in  fact 
easily  arrive  at  the  assumption  that  quite  peculiar  factors 
were  here  at  work.  One  excellent  reason  why  this  mysteri- 
ous operation  of  the  future  at  a  distance  cannot  be  com- 
pared with  any  physical  relation,  is  that  the  operation  does 
not  take  place  exactly  and  without  exception,  since  many 
organisms  prepare  themselves  for  a  later  stage  of  their  life, 
but  are  destroyed  before  attaining  it.  It  is  impossible  to 
regard  something  which  is  not  determined  for  ourselves,  or 
is  only  partially  determined,  namely  the  uncertain  past  or 
the  uncertain  future,  as  being  the  determining  factor  in  a 
present  process  which  is  going  on  before  our  eyes.  But 
when  we  reflect  that  the  processes  in  the  life  of  generations 
return  periodically,  we  see  that  the  conception  of  a  par- 
ticular stage  of  life  as  being  in  the  future  and  operating  at 


THE  ANALYSIS  OF  SENSATIONS          95 

a  distance  is  an  arbitrary  and  hazardous  conception,  and 
that  the  stage  of  life  in  question  can  also  be  regarded  as  a 
process  in  the  past,  as  something  given  which  has  left  its 
traces  behind.  In  this  way  the  element  of  the  unfamiliar 
and  incomprehensible  is  greatly  decreased.  What  we  then 
have  is  not  a  possible  future  which  might  produce  an  effect, 
but  a  past  which  certainly  has  recurred  countless  times, 
and  which  certainly  has  produced  an  effect. 

As  an  example  of  our  contention  that  Physics  is  capable 
of  co-operating  fruitfully  in  the  solution  of  what  are  appar- 
ently specifically  biological  problems,  we  have  only  to 
remember  the  remarkable  progress  made  by  experimental 
embryology  and  the  mechanism  of  development  with  its 
physico-chemical  methods.1  We  have  another  very  remark- 
able fact  in  O.  Wiener's  demonstration  of  the  probable 
connexion  between  color-photography  and  color-adaptation 
in  nature.2  By  means  of  stationary  light-waves  stratification 
may  be  formed  in  a  medium  that  is  sensitive  to  light,  and 
then  the  incident  light  may  be  reflected  back  as  an  inter- 
ference-color;  but  there  is  yet  another  way  in  which  a 
coloration  corresponding  to  the  illumination  may  arise. 
Of  materials  that  are  sensitive  to  light,  there  are  some 
which  can  take  on  almost  any  hue.  When  such  materials 
are  exposed  to  a  colored  illumination,  they  retain  the  color 
of  the  illumination,  because  they  do  not  absorb  the  rays 
of  the  same  color  as  themselves,  and  consequently  the 
light  is  incapable  of  producing  any  further  change  in 

1  Cp.  W.  Roux,  Vortrdge  und  Aufsatze  iiber  Entivickelungsmechanik 
der  Organismen,  Leipzig,  W.  Engelmann,  1905. 

2  O.  Wiener,   "  Farbenphotographie  und  Farbenanpassung  in  der 
Natur,"  Wiedemann's  AnnaZen,  Vol.  LV.,  1895,  p.  225. 


96          THE  ANALYSIS  OF  SENSATIONS 

them.  According  to  Poulton's  observations  l  it  is  probable 
that  many  of  the  adaptive  colors  of  chrysalises  arise  in  this 
manner.  Thus  in  such  cases  we  do  not  need  to  look  far 
afield  from  the  means  that  produce  the  effect,  in  order  to 
find  the  "  purpose  "  that  is  attained.  Avoiding  all  rashness 
of  statement,  we  may  say  that  the  equilibrium  is  determined 
by  the  circumstances  under  which  it  is  attained. 


8. 

The  conceptions  of  "  effective  cause  "  and  of  "  purpose  " 
both  have  their  origin  in  animistic  views,  as  is  quite  clearly 
seen  from  the  scientific  attitude  of  antiquity.  The  savage, 
no  doubt,  does  not  puzzle  his  head  by  reflecting  on  his  own 
movements,  which  seem  to  him  quite  spontaneous,  natural 
and  self-evident.  But  as  soon  as  he  perceives  unexpected 
and  striking  movements  in  nature,  he  instinctively  interprets 
these  movements  on  the  analogy  of  his  own.  In  this  way 
the  distinction  between  his  own  and  someone  else's  volition 
begins  to  dawn  upon  him.2  Gradually  the  similarities  and 
differences  between  physical  and  biological  processes  stand 

1  Poulton,  The  Colors  of  Animals,  London,  1890. 

-I  once  set  a  Holtz  electrical  machine  going  for  the  benefit  of  one  of 
my  boys  when  he  was  about  three  years  old.  He  was  delighted  by  the 
dancing  sparks.  But  when  I  let  go  the  machine  and  it  went  on  rotating 
by  itself,  he  started  back  in  terror  and  apparently  thought  it  was  alive  : 
"It  goes  by  itself!"  he  exclaimed,  in  startled  and  anxious  tones. 
Perhaps  it  is  the  same  with  dogs  when  they  run  barking  after  every 
moving  cart.  (For  another  plausible  explanation,  which  does  not 
agree  with  this  view,  see  Zell,  Sinddie  Tiere  unvernunftig?  Kosmos- 
verlag,  p.  38. )  I  remember  that  when  I  was  about  three  years  old  I 
was  frightened  when  the  elastic  seed-capsule  of  a  plant  of  garden- 
balsam  opened  on  being  pressed,  and  pinched  my  finger.  It  seemed 
to  me  alive,  like  an  animal. 


THE  ANALYSIS  OF  SENSATIONS          97 

out  alternately  with  ever  greater  clearness  against  the  back- 
ground of  the  fundamental  scheme  of  volitional  action. 
Where  volitional  action  is  conscious,  cause  and  purpose 
still  coincide.  As  regards  physical  processes,  their  great 
simplicity  and  their  susceptibility  to  calculation  cause  the 
animistic  conception  to  fade  gradually  away.  Through 
a  series  of  rigid  forms  the  conception  of  cause  merges  by 
degrees  into  the  conceptions  of  dependence  and  function. 
It  is  only  for  the  phenomena  of  organic  life,  which  offer 
less  resistance  to  the  animistic  view,  that  the  conception 
of  purpose,  the  notion  of  an  activity  that  is  conscious  of  its 
end,  is  still  maintained ;  and  where  conscious  purposive 
action  cannot  be  ascribed  to  the  organism  itself,  some 
higher  entity  that  strives  towards  a  goal  (Nature,  or  the 
like)  is  assumed  as  watching  over  the  organism  and  guiding 
its  activities. 

Animism,  or  anthropomorphism,  is  not  an  epistomological 
fallacy ;  if  it  were,  every  analogy  would  be  such  a  fallacy. 
The  fallacy  lies  merely  in  the  application  of  this  view  to 
cases  in  which  the  premises  for  it  are  lacking  or  are  not 
sufficient.  Nature,  in  producing  man,  has  created  a  pro- 
fusion of  analogies  between  lower,  and  doubtless  also 
between  higher,  stages  of  evolution. 

When  any  process  which  is  completely  determined  by 
the  circumstances  of  the  moment,  and  which  remains 
limited  to  itself  without  further  consequences,  occurs  in 
an  inorganic,  or  even  in  an  organic,  body,  we  should 
scarcely  speak  of  a  purpose, — as,  for  instance,  when  a 
sensation  of  light  or  a  muscular  contraction  is  excited  by 
a  stimulus.  But  when  the  hungry  frog  snaps  at  the  fly 
which  it  sees,  and  swallows  and  digests  it,  we  naturally 


98          THE  ANALYSIS  OF  SENSATIONS 

adopt  the  notion  of  purposive  action.  Purposiveness  only 
comes  in  when  the  organic  functions  are  resolved  into 
one  another,  when  they  are  seen  as  interconnected,  as  not 
limited  to  the  immediate,  as  proceeding  by  way  of  detours. 
In  the  sphere  of  the  organic  a  much  larger  section  of  the 
world-process  is  manifested ;  we  are  aware  of  the  influence 
of  a  wider  spatial  and  temporal  environment.  That  is  why 
the  organic  is  more  difficult  to  understand.  Real  under- 
standing is  attained  when,  and  only  when,  we  have  suc- 
ceeded in  resolving  the  complex  into  its  immediately 
connected  parts.  Accordingly,  the  peculiar  characteristics 
of  the  organic  must  be  regarded  only  as  provisional  clues. 
The  perusal  of  recent  biological  writings  (Driesch,  Reinke, 
etc.),  though  perhaps  they  are  opposed  to  my  own 
tendencies,  only  confirms  me  in  this  view.  And  if  teleo- 
logical  investigation  can  only  be  provisional,  the  same  is 
true  of  historical  investigation  also,  since  all  historical 
research  needs  to  be  supplemented  by  causal  explanation, 
— a  point  which  is  very  properly  emphasized  in  Loeb's 
biological  works,  and  in  K.  Menger's  writings  on  economics. 


Every  organism  together  with  its  parts  is  subject  to  the 
laws  of  physics.  Hence  the  legitimate  attempt  gradually 
to  conceive  of  an  organism  as  something  physical,  and  to 
establish  the  consideration  of  it  in  a  "causal"  point  of 
view  as  alone  valid.  But  whenever  we  try  to  do  this  we 
are  always  brought  face  to  face  with  the  peculiar  character- 
istics of  the  organic,  for  which  no  analogy  can  be  found  in 
the  physical  phenomena  of  "lifeless"  nature,  so  far  as  they 


THE  ANALYSIS  OF  SENSATIONS          99 

have  been  investigated  at  present.  Every  organism  is  a 
system  that  is  able  to  maintain  its  peculiar  properties, — its 
chemical  composition,  its  temperature  and  so  forth, — in  the 
face  of  external  influences,  and  which  manifests  a  state  of 
dynamic  equilibrium  of  considerable  stability.1  By  an 
expenditure  of  energy  the  organism  is  able  to  draw  more 
energy  to  itself  from  its  environment,  and  thus  to  replace 
the  loss  of  energy  by  an  equal  or  a  greater  amount.2  A 
steam-engine  which  should  fetch  its  coal  itself  and  heat 
itself,  is  only  a  feeble  and  artificial  image  of  an  organism. 
The  organism  possesses  these  properties  even  in  its  minuter 
parts ;  it  regenerates  itself  from  these  parts ;  that  is  to  say, 
it  grows  and  propagates  itself.  Physics  therefore  still  has 
much  that  is  new  to  learn  from  a  study  of  the  organic 
before  it  is  in  a  position  to  control  the  organic.3 

The  best  physical  image  of  a  living  process  is  still 
afforded  by  a  conflagration,  or  some  similar  process,  which 
automatically  transfers  itself  to  the  environment.  A  con- 
flagration keeps  itself  going,  produces  its  own  combustion- 
temperature,  brings  neighbouring  bodies  up  to  that  tempera- 
ture and  thereby  drags  them  into  the  process,  assimilates 
and  grows,  expands  and  propagates  itself.  Nay,  animal 
life  itself  is  nothing  but  combustion  in  complicated  cir- 
cumstances .4 


10. 

Let  us  compare  our  volitional  action  with  some  reflex 

1  Hering,  Vorgdnge  in  der  lebendigen  Substanz,  Lotos,  Prague,  1888. 

2  Hirth,  Energetische  Epigenesis,  Munich,  1898,  pp.  x.,  xi. 

3  Hering,  Zur  Theorie  der  Nerventatigkeit,  Leipzig,  1899. 

4Cf.  Ostwald,  Naturphilo  sophie,  and  the  work  of  Roux  cited  on 
p.  95,  above. 


TOO        THE  ANALYSIS  OF  SENSATIONS 

movement  which  we  have  observed  in  ourselves,  and  which 
causes  us  surprise  when  it  occurs,  or  with  the  reflex  move- 
ment of  an  animal.  In  the  two  latter  cases  we  can  detect 
an  inclination  to  regard  the  whole  process  as  physically 
determined  by  the  momentary  circumstances  of  the 
organism.  Now  what  we  call  volition  is  nothing  more 
than  the  totality  of  those  conditions  of  a  movement  which 
enter  partly  into  consciousness  and  are  connected  with  a 
prevision  of  the  result.  If  we  analyse  these  conditions,  so 
far  as  they  enter  into  consciousness,  we  find  nothing  more 
than  memory-traces  of  former  experiences  and  their  inter- 
connection (association).  It  seems  that  the  preservation 
of  such  traces  and  their  associations  is  a  fundamental 
function  of  elementary  organisms,  even  though,  in  the  case 
of  such  organisms,  we  are  no  longer  able  to  speak  of 
consciousness  or  of  any  arrangement  in  a  system  of 
memories. 

If  we  may  take  memory  and  association,  in  Hering's 
wider  sense,  to  be  fundamental  properties  of  elementary 
organisms,  then  adaptation  would  become  intelligible.1 
Favourable  combinations  occur  more  often  than  in  the 
ratio  of  compound  probability,  and  remain  associated. 
The  presence  of  food,  the  feeling  of  satiety,  and  swallowing 
movements  remain  interconnected.  The  fact  that  phylo- 
genesis is  repeated  in  ontogenesis  in  an  abbreviated  form, 
would  constitute  a  parallel  to  the  well-known  phenomenon 
by  which  thoughts  return  by  preference  along  the  paths 
which  they  have  once  taken,  similar  thoughts  under  similar 
conditions  evoking  similar  thoughts.  We  do  not  indeed 

1  Hering,  Ueber  das  Gcdachtnis  als  allegemeine  runktion  der  organi- 
sierten  Materie,  Vienna,  1870. 


THE  ANALYSIS  OF  SENSATIONS        101 

know  what  are  the  physical  counterparts  to  memory  and 
association.  All  the  explanations  that  have  been  attempted 
are  very  much  forced.  In  this  respect  it  seems  as  if-  there 
were  almost  no  analogy  between  the  organic  and  the  in- 
organic. It  is  possible,  however,  that,  in  the  physiology 
of  the  senses,  psychological  observation  on  the  one  side 
and  physical  observation  on  the  other,  may  make  such 
progress  that  they  will  ultimately  come  into  contact,  and 
that  in  this  way  new  facts  may  be  brought  to  light.1  The 
result  of  this  investigation  will  not  be  a  dualism,  but  rather 
a  science  which,  embracing  both  the  organic  and  the 
inorganic,  shall  interpret  the  facts  that  are  common  to  the 
two  departments. 

1  I  first  tentatively  suggested  this  notion,  though  still  in  terms  of 
Fechner's  theories,  in  the  Kompendiiim  der  Physikfur  Mediziner, 
1863,  p.  234. 


VI.  THE  SPACE  SENSATIONS  OF 
THE  EYE. 


i. 


tree  with  its  hard,  rough,  grey  trunk,  its  many 
-L  branches  swayed  by  the  wind,  its  smooth,  soft, 
shining  leaves,  appears  to  us  at  first  a  single,  indivisible 
whole.  In  like  manner,  we  regard  the  sweet,  round,  yellow 
fruit,  the  warm,  bright  fire,  with  its  manifold  moving 
tongues,  as  a  single  thing.  One  name  designates  the 
whole,  one  word  draws  forth  from  the  depths  of  oblivion 
all  the  associated  memories  at  once,  as  if  they  were  strung 
upon  a  single  thread. 

The  reflexion  of  the  tree,  the  fruit,  or  the  fire  in  a  mirror 
is  visible,  but  not  tangible.  When  we  turn  our  glance 
away  or  close  our  eyes,  we  can  touch  the  tree,  taste  the 
fruit,  feel  the  fire,  but  we  cannot  see  them.  Thus  the 
apparently  indivisible  thing  separates  into  parts,  which  are 
not  only  attached  to  one  another  but  also  to  other  condi- 
tions. The  visible  is  separable  from  the  tangible,  from 
that  which  may  be  tasted,  etc. 

What  is  merely  visible  also  appears  at  first  sight  to  be  a 
single  thing.  But  we  may  see  a  round,  yellow  fruit  together 
with  a  yellow,  star-shaped  blossom.  A  second  fruit  may  be 
just  as  round  as  the  first,  but  is  green  or  red.  Two  things 
may  be  alike  in  color  but  unlike  in  form ;  they  may  be 

different  in  color  but  like  in  form.      Thus   sensations  of 

102 


THE  ANALYSIS  OF  SENSATIONS        103 

sight  are  separable  into  color-sensations  and  space -sensa- 
tions, which  are  different  from  one  another  even  though 
they  cannot  be  represented  in  isolation  from  another. 


2. 

Color-sensation,  into  the  details  of  which  we  shall  not 
enter  here,  is  essentially  a  sensation  of  favorable  or  un- 
favorable chemical  conditions  of  life.  In  the  process  of 
adaptation  to  these  conditions,  color-sensation  has  probably 
been  developed  and  modified.1  Light  introduces  organic 

1  Compare  Grant  Allen,  The  Color-Sense,  London,  Triibner  &  Co., 
1879.  The  attempt  of  H.  Magnus  to  show  a  considerable  develop- 
ment of  the  color-sense  within  historical  times,  cannot,  I  think,  be 
regarded  as  felicitous.  Immediately  after  the  appearance  of  the 
writings  of  Magnus,  I  corresponded  with  a  philologist,  Prof.  F.  Polle 
of  Dresden,  on  this  subject,  and  both  of  us  soon  came  to  the  conclusion 
that  the  views  of  Magnus  could  not  hold  their  own  before  the  critical 
examination  either  of  natural  science  or  of  philology.  As  each  of  us 
left  the  publication  of  the  results  of  our  discussion  to  the  other,  these 
were  never  made  public.  Meantime,  however,  the  matter  has  been 
disposed  of  by  E.  Krause,  and  in  detail  by  A.  Marty.  I  shall  take  the 
liberty  of  adding  only  a  few  brief  remarks.  From  defects  of  termin- 
ology we  cannot  infer  the  absence  of  corresponding  qualities  of  sensation. 
Terms,  even  to-day,  are  always  indistinct,  hazy,  defective,  and  few  in 
number,  where  there  is  no  necessity  for  sharp  discrimination.  The 
color-terminology  of  the  countryman  of  to-day,  and  his  terminology  of 
sensations  in  general,  is  no  more  developed  than  that  of  the  Greek 
poets.  The  peasants  of  the  Marchfeld  say,  for  example,  as  I  have 
often  proved  by  personal  experience,  that  salt  is  "sour,"  because  the 
expression  "salty"  is  not  familiar  to  them.  The  terminology  of 
colors  must  not  be  looked  for  in  the  poets,  but  in  technical  works. 
And,  furthermore,  as  my  colleague  Benndorf  has  remarked,  we  must 
not  take  an  enumeration  of  vase -pigments  for  an  enumeration  of  all 
colors,  as  does  Magnus.  When  we  consider  the  polychromy  of  the 
ancient  Egyptians  and  Pompeiians,  when  we  take  into  account  the 
fact  that  these  decorations  can  scarcely  have  been  produced  by  the 


104        THE  ANALYSIS  OF  SENSATIONS 

life.  The  green  chlorophyll  and  the  (complementary)  red 
haemoglobin  play  a  prominent  part  in  the  chemical  pro- 
cesses of  the  plant-body  and  in  the  chemical  reactions  of 
the  animal  body.  The  two  substances  present  themselves 
to  us  in  the  most  varied  modifications  of  tint.  The  dis- 
covery of  the  visual  purple,  and  observations  in  photography 
and  photo-chemistry,  allow  us  to  conceive  visual  processes 
also  as  chemical  processes.  The  r61e  which  color  plays  in 
analytical  chemistry,  in  spectrum-analysis,  in  crystallography, 
is  well  known.  It  suggests  a  new  conception  for  the  so- 
called  vibrations  of  light,  according  to  which  they  should 
be  regarded,  not  as  mechanical,  but  as  chemical  vibrations, 
as  successive  union  and  separation,  as  an  oscillatory  process 
of  the  same  sort  that  takes  place,  though  only  in  one  direc- 
tion, in  photo-chemical  phenomena.  This  conception, 
which  is  substantially  supported  by  recent  investigations  in 
anomalous  dispersion,  accords  with  the  electro-magnetic 

color-blind,  when  we  note  that  Pompeii  was  buried  in  ashes  only 
seventy  years  after  Vergil's  death,  whilst  Vergil  on  this  theory  is  sup- 
posed to  have  been  nearly  color-blind,  the  untenability  of  the  whole 
conception  is  sufficiently  apparent.  The  question  has  lately  been  taken 
up  again,  with  recourse  to  fuller  authorities,  by  W.  Schultz  (Das 
Farbenempjind^lngs system  der  Hellenen,  Leipzig,  1904).  Applications 
of  the  Darwinian  theory  are  also  to  be  made  with  caution  in  another 
direction.  We  like  to  picture  to  ourselves  a  condition  in  which  the 
color-sense  is  lacking,  or  in  which  little  color-sense  exists,  as  preceding 
another  in  which  the  color-sense  is  highly  developed.  For  the  beginner 
it  is  natural  to  proceed  from  the  simple  to  the  complex.  But  this  is 
not  necessarily  the  path  of  Nature.  The  color-sense  exists,  and  it  is 
probably  variable.  But  whether  it  is  being  enriched  or  impoverished — 
who  can  tell?  Is  it  not  possible  that,  with  the  awakening  of  intelli- 
gence and  the  use  of  artificial  contrivance,  the  whole  development  will 
be  shifted  to  the  intellect, — which  certainly  is  chiefly  called  into  play 
from  this  point  on, — and  that  the  development  of  the  lower  organs  of 
man  will  be  relegated  to  second  place  ? 


THE  ANALYSIS  OF  SENSATIONS        105 

theory  of  light.  In  the  case  of  electrolysis,  in  fact,  chemistry 
yields  the  most  intelligible  conception  of  the  electric  current 
by  regarding  the  two  components  of  the  electrolyte  as  pass- 
ing through  each  other  in  opposite  directions.  It  is  likely, 
therefore,  that  in  a  future  theory  of  colors,  many  biologico- 
psychological  and  chemico-physical  threads  will  be  united. 


Adaptation  to  the  chemical  conditions  of  life  which 
manifest  themselves  in  color,  renders  locomotion  necessary 
to  a  far  greater  extent  than  adaptation  to  those  which  mani- 
fest themselves  through  taste  and  smell.  At  least  this  is  so 
in  the  case  of  man,  which  is  here  in  question,  and  as  to 
which  alone  a  direct  and  certain  judgment  is  within  our 
power.  The  close  association  of  space-sensation  (a 
mechanical  factor)  with  color-sensation  (a  chemical  factor) 
is  thus  rendered  intelligible.  We  shall  now  proceed  to  the 
analysis  of  optical  space-sensations. 


In  examining  two  figures  which  are  alike  but  differently 
colored  (for  example,  two  letters  of  the  same  size  and  shape, 
but   of  different   colors),  we   recognize 
their  sameness  of  form  at  the  first  glance, 
in  spite  of  the  difference  of  color-sensa- 
tion.    The  sight-perceptions,  therefore, 
must  contain  some  identical  sensation- 
components.     These  are  the  space-sensations — which  are 
the  same  in  the  two  cases. 


IB 


io6        THE  ANALYSIS  OF  SENSATIONS 


5- 


We  will  now  investigate  the  character  of  the  space- 
sensations  that  physiologically  condition  the  recognition  of 
a  figure.  First,  it  is  clear  that  this  recognition  is  not  the 
result  of  geometrical  considerations — which  are  a  matter, 
not  of  sensation,  but  of  intellect.  On  the  contrary,  the 
space-sensations  in  question  serve  as  the  starting-point  and 
foundation  of  all  geometry.  Two  figures  may  be  geometri- 
cally congruent,  but  physiologically  quite  different,  as  is 


Fig.  3- 

shewn  by  the  two  adjoined  squares  (Fig.  3),  which  could 
never  be  recognized  as  the  same  without  mechanical  and 
intellectual  operations.1  A  few  simple  experi- 
ments  will  render  us  familiar  with  the  relations 
here  involved.  Look  at  the  spot  in  Fig.  4. 
Place  the  same  spot  twice  or  several  times  in 
exactly  the  same  position  in  a  row  (Fig.  5)  ;  the 
result  is  a  peculiar,  agreeable  impression,  and  we  recog- 
nize at  once  and  without  difficulty  the  identity  of  all  the 

1  Compare  my  brief  paper,  Ueber  das  Sehen  von  Lagenund  Winkeln, 
in  the  Sitzungsberichte  der  Wiener  Akademie,  Vol.  XLIIL,  1861,  p.  215. 


Fig.  4- 


THE  ANALYSIS  OF  SENSATIONS        107 


Fig.  5- 

figures.     When,   however,  we   turn   one   spot   far  enough 
round  with  respect  to  the  other  (Fig.  6),  their  identity  of 
form  is  not  recognizable  without  intellectual 
assistance.       On  the   other  hand,  if  we 
place  two  of  the  spots  in  positions  sym- 
metrical   to    the    median    plane    of  the 
observer  (Fig.  7)  the  relationship  of  form 
is  strikingly  apparent.      But  if  the  plane 
of  symmetry  diverges    considerably  from 
the  median  plane  of  the   observer,  as  in 
Fig.  8,  the   affinity  of  form   is  recogniz- 
able only  by  turning  the  figure  around  or  by  an  intellectual 
act.     On  the  other  hand,  the  affinity  of  form  is 
again  apparent  on  contrasting   with  such  a  spot 
the  same  spot  rotated  through  an  angle  of  180° 
in  the  same  plane  (Fig.  9).     In  this  case  we  have 
the  so-called  centric  symmetry. 

If  we  reduce  all  the   dimensions   of  the  spot 
proportionately,  we  obtain  a  geometrically  similar 
spot.     But  as  the  geometrically  congruent  is  not 
necessarily  physiologically  (optically)  congruent,  nor 
the  geometrically  symmetrical  necessarily  optically 
symmetrical,  analogously  the  geometrically  similar 
is  not  necessarily  optically  similar.     It  is  only  when 
the  two  geometrically  similar  spots  are  placed  beside     Fi£-  9- 
each  other  in  the  same  relative  positions  (Fig.  10),  that  they 
will  also  appear  optically  similar.     Turning  one  of  the  spots 


io8        THE  ANALYSIS  OF  SENSATIONS 

round  destroys  the  resemblance  (Fig.  n).     If  we  substitute 
for  one  of  the  spots  a  spot  symmetrical  to  the  other  in 

respect  of  the  median  plane 
of  the  observer  (Fig.  12),  a 
symmetrical  similarity  will  be 
produced  which  has  also  an 
optical  value.  The  turning 
of  one  of  the  figures  through 
1 80°  in  its  own  plane,  pro- 
ducing thereby  centrically 
symmetrical  similarity,  has 
also  a  physiologico-optical  value  (Fig.  13). 

6. 

In  what,  now,  does  the  essential  nature  of  optical  similarity, 
as  contrasted  with  geometrical  similarity,  consist  ?  In  geo- 
metrically similar  figures,  all  homologous  distances  are 
proportional.  But  that  is  an  affair  of  the  intellect,  not  of 
sensation.  If  we  place  beside  a  triangle  with  the  sides 
a,  b,  £,  a  triangle  with  the  sides  20,  26,  2C,  we  do  not 
recognize  this  simple  relation  between  the  two  immediately, 
but  intellectually,  by  measurement.  If  the  similarity  is  to 
become  optically  perceptible,  the  proper  position  must  be 
added.  That  a  simple  relation  of  two  objects  for  the 
intellect  does  not  necessarily  condition  a  similarity  of 
sensation,  may  be  perceived  by  comparing  two  triangles 
having  respectively  the  sides,  a,  b,  c,  and  a  +  m,l>  +  m,£  +  m. 
The  two  triangles  do  not  look  at  all  alike.  Similarly  all 
conic  sections  do  not  look  alike,  although  all  stand  in  a 
simple  geometric  relation  to  each  other ;  still  less  do  curves 
of  the  third  order  exhibit  optical  similarity,  etc. 


THE  ANALYSIS  OF  SENSATIONS        109 


The  geometrical   similarity  of  two  figures  is  determined 
by  all  their  homologous  lines  being  proportional  or  by  all 
their  homologous  angles  being  equal.    But  to  appear  optically 
similar  the  figures  must  also 
be  similarly  situated^  that  is 
all  their   homologous  direc- 
tions must  be  parallel  or,  as 
we  prefer  to  say,  must  be  the 
same  (Fig.  14).    The  import- 
ance of  direction  for  sensation  will  be  evident  upon  a  careful 
consideration  of  Fig.    3.      It  is  by  identity  of  direction, 
accordingly,  that  are  determined  the  identical  space-sensa- 
tions which   are  characteristic  of  the  physiologico-optical 
similarity  of  the  figures.1 

We  may  obtain  an  idea  of  the  physiological  significance 
of  the  direction  of  a  given  straight  line  or  curve-element, 
by  the  following  reflexion.  Let  y^=f(x)  be  the  equation 
of  a  plane  curve.  We  can  read  at  a  glance  the  course  of 
the  values  of  dy\dx  on  the  curve,  for  they  are  determined 

1  Some  forty  years  ago,  in  a  society  of  physicists  and  physiologists,  I 
proposed  for  discussion  the  question,  why  geometrically  similar  figures 
were  also  optically  similar.  I  remember  quite  well  the  attitude  taken 
with  regard  to  this  question,  which  was  accounted  not  only  superfluous, 
but  even  ludicrous.  Nevertheless,  I  am  now  as  strongly  convinced  as 
I  was  then  that  this  question  involves  the  whole  problem  of  form-vision. 
That  a  problem  cannot  be  solved  which  is  not  recognized  as  such  is 
clear.  In  this  non-recognition,  however,  is  manifested,  in  my  opinion, 
that  one-sided  mathematico-physical  direction  of  thought,  which  alone 
accounts  for  the  opposition,  from  so  many  sides  and  extending  over  so 
many  years,  instead  of  cheerful  acceptance,  with  which  the  writings  of 
Hering  have  been  received- 


no        THE  ANALYSIS  OF  SENSATIONS 

by  its  steepness ;  and  the  eye  gives  us,  likewise,  qualitative 
information  concerning  the  values  of  d2yjdx2t  for  they  are 
characterized  by  the  curvature.  The  question  naturally 
presents  itself,  why  can  we  not  arrive  at  as  immediate 
conclusions  concerning  the  values  d3y/dx3,  d4y/dx\  etc. 
The  answer  is  easy.  What  we  see  is  of  course  not  the 
differential  coefficients,  which  are  an  intellectual  affair,  but 
only  the  direction  of  the  curve-elements,  and  the  deviation 
of  the  direction  of  one  curve-element  from  that  of  another. 
In  fine,  since  we  are  immediately  cognisant  of  the 
similarity  of  figures  lying  in  similar  positions,  and  are  also 
able  to  distinguish  at  once  the  special  case  of  congruity, 
therefore  our  space-sensations  yield  us  information  con- 
cerning identity  or  difference  of  directions  and  equality  or 
inequality  of  dimensions. 

8. 

It  is  a  priori  extremely  probable  that  sensations  of  space 
are  connected  in  some  way  with  the  motor  apparatus  of 
the  eye.  Without  entering  into  particulars,  we  may  observe, 
first,  that  the  whole  apparatus  of  the  eye,  and  especially  the 
motor  apparatus,  is  symmetrical  with  respect  to  the  median 
plane  of  the  head.  Hence,  symmetrical  movements  of 
looking  will  be  connected  with  like  or  approximately  like 
space-sensations.  Children  constantly  confound  the  letters 
b  and  d,  p  and  q.  Adults,  too,  do  not  readily  notice  a 
change  from  left  to  right,  unless  some  special  points  of 
apprehension  for  sensev  or  intellect  make  it  noticeable. 
The  symmetry  of  the  motor  apparatus  of  the  eye  is  very 
perfect.  The  like  excitation  of  its  symmetrical  organs 
would,  by  itself,  scarcely  account  for  the  distinction  of 


THE  ANALYSIS  OF  SENSATIONS        in 

right  and  left.  But  the  whole  human  body,  especially  the 
brain,  is  affected  with  a  slight  asymmetry, — which  leads, 
for  example,  to  the  preference  of  one  (generally  the  right) 
hand,  in  motor  functions.  And  this  leads,  again,  to  a 
further  and  better  development  of  the  motor  functions  of 
the  right  side,  and  to  a  modification  of  the  attendant 
sensations.  After  the  space-sensations  of  the  eye  have 
become  associated,  through  writing,  with  the  motor  sensa- 
tions of  the  right  hand,  a  confusion  of  those  vertically 
symmetrical  figures  with  which  the  art  and  habit  of  writing 
are  concerned  no  longer  ensues.  This  association  may 
even  become  so  strong  that  the  memories  follow  only  the 
accustomed  tracks,  and  we  read,  for  example,  the  reflexion 
of  written  words  in  a  mirror  only  with  the  greatest  difficulty. 
The  confusion  of  right  and  left  still  occurs,  however,  with 
regard  to  figures  which  have  no  motor,  but  only  a  purely 
optical  (for  example,  ornamental)  interest.  A  noticeable 
difference  between  right  and  left  must  be  felt,  moreover, 
by  animals,  as  in  many  predicaments  they  have  no  other 
means  of  finding  their  way.  How  similar,  moreover,  are 
the  sensations  connected  with  symmetrical  motor  functions 
is  easily  remarked  by  the  attentive  observer.  If,  for 
example,  because  my  right  hand  happens  to  be  engaged, 
I  grasp  a  micrometer-screw  or  a  key  with  my  left  hand, 
I  am  certain  (unless  I  reflect  beforehand)  to  turn  it  in 
the  wrong  direction, — that  is,  I  always  perform  the  move- 
ment which  is  symmetrical  to  the  usual  movement,  con- 
fusing the  two  because  of  the  similarity  of  the  sensation. 
The  observations  of  Heidenhain  regarding  the  reflected 
writing  of  persons  hypnotized  on  one  side  should  also  be 
cited  in  this  connexion. 


H2         THE  ANALYSIS  OF  SENSATIONS 


The  idea  that  the  distinction   between   right   and   left 
depends   upon   an    asymmetry,    and    possibly   in   the   last 
resort  upon  a  chemical  difference,  is  one  which  has  been 
present  to  me  from  my  earliest  years.     I  gave  expression 
to  it  in  the  first  lectures  I  ever  delivered,  in  1861.     Since 
then  this  idea  has  forced  itself  upon  me  again  and  again. 
I  learned  by  chance  from  a  retired  army-officer  that  on  dark 
nights  or  in  snow-storms,   when  external  landmarks  are 
absent,  troops  will  move  approximately  in  a  circle  of  large 
radius  so  that  they  almost  return  to  their  point  of  departure, 
though  all  the  time  they  are  under  the  impression  that 
they  are  marching  straight  forward.     An  analogous  pheno- 
menon is  narrated  in  Tolstoi's  story,  Master  and  Servant. 
Probably  the  only  way  to  understand  these  phenomena  is 
to  assume  a  slight  motor  asymmetry.     They  are  analogous 
to  the  way  in  which  a   ball  with  a  slight  deviation  from 
the  true  cylindrical  shape  rolls  in  a  circle  of  large  radius. 
This  is  actually  the  way  in  which  the  matter  is  regarded 
by  F.  O.  Guldberg,1  who  has  carried  out  detailed  researches 
on  the  phenomena  presented  in  this  connexion  by  human 
beings  and  animals   that   have   lost   their  way.      Human 
beings  and  animals  that  have  lost  their  direction  move, 
almost  without  exception,  nearly  in  circles,  of  which  the 
radii  vary  according  to  the  species,  while  the  centre  lies 
sometimes  on  the  left  hand  of  the  individual  travelling 
along    the    circumference,    and   sometimes   on   his   right, 

1  F.  O.  Guldberg,  "  Die  Zirkularbewegung,"  Zeitschrift  far  Biologic, 
Vol.  XXV.,  p.  419,  1897.  Dr  W.  Pauli  drew  my  attention  to  this 
article  in  conversation. 


THE  ANALYSIS  OF  SENSATIONS        113 

according  to  the  individual  and  the  species.  According 
to  Guldberg  we  have  here  a  teleological  device  to  help 
parents  to  find  their  hungry  young  again  when  they  have 
been  lost.  Experiments  on  the  lower  animals,  with  whom 
this  factor  is  absent,  would  therefore  be  interesting.  For 
the  fest,  we  should  expect,  on  grounds  of  general  proba- 
bility, to  find  imperfect  symmetry  in  the  lower  animals  also. 
Again,  Loeb's  researches  "  On  the  Spatial  Feeling  of 
the  Hand," J  have  taught  us,  amongst  other  things,  that 
when  the  eyes  are  bandaged,  a  given  movement  of  the 
right  hand,  if  imitated  by  the  left,  is  always  reproduced 
in  an  exaggerated  or  a  diminished  form ;  the  degree  of 
exaggeration  or  diminution  varying  with  the  individual. 
Loeb  thinks  that  the  phenomena  of  regeneration  allow  us 
to  infer  that  the  distinction  between  right  and  left  is 
specific.  I  am  certain,  however,  that  I  personally  have 
never  regarded  it  as  a  merely  geometrical  and  quantitative 
motor  difference. 

10. 

With  looking  upwards  and  looking  downwards,  funda- 
mentally different  space  -  sensations  are  associated,  as 
ordinary  experience  shows.  This  is,  moreover,  compre- 
hensible, since  the  motor  apparatus  of  the  eye  is  asym- 
metrical with  respect  to  a  horizontal  plane.  The  direction 
of  gravity  also  is  so  very  decisive  and  important  for  the 
motor  apparatus  of  the  rest  of  the  body  that  this  fact  has 
assuredly  also  found  its  expression  in  the  apparatus  of  the 
eye,  which  serves  the  rest.  It  is  well  known  that  the 

1  Loeb,  "  Ueber  den  Ftihlraum  der  Hand,"  Pflliger's  Archiv,  Vols, 
XLI.  and  XLVI. 
H 


H4        THE  ANALYSIS  OF  SENSATIONS 

symmetry  of  a  landscape  and  of  its  reflexion  in  water  is 
not  felt.  The  portrait  of  a  familiar  personage,  when  turned 
upside  down,  is  strange  aid  puzzling  to  a  person  who 
does  not  recognize  it  intellectually.  If  we  place  ourselves 
behind  the  head  of  a  person  lying  upon  a  couch,  and 
unreflectingly  give  ourselves  up  to  the  impression  which 
the  face  makes  upon  us,  we  shall  find  that  our  impression 
is  altogether  strange,  especially  when  the  person  speaks. 
The  letters  b  and  /,  and  d  and  ^,  are  not  confused  even 
by  children. 

Our  previous  remarks  concerning  symmetry,  similarity, 
and  the  rest,  naturally  apply  not  only  to  plane  figures,  but 
also  to  those  in  space.  Hence,  we  have  yet  a  remark  to 
add  concerning  the  sensation  of  space-depth.  The  sight 
of  something  at  a  distance  causes  different  sensations  from 
the  sight  of  something  near  at  hand.  These  sensations 
must  not  be  confused,  because  of  the  supreme  importance 
of  the  difference  between  near  and  far,  both  for  animals  and 
human  beings.  They  cannot  be  confused,  because  the 
motor  apparatus  is  asymmetrical  with  respect  to  a  plane 
perpendicular  to  the  direction  from  front  to  rear.  It  is  a 
common  experience  that  a  portrait-bust  of  a  person  whom 
we  know  quite  well  cannot  be  replaced  by  the  mould 
in  which  the  bust  is  cast,  and  this  experience  is  quite 
analogous  to  the  observations  consequent  upon  the  inver- 
sion of  objects. 

ii. 

If  we  suppose  that  identical  dimensions  and  identical 
directions  excite  identical  space-sensations,  and  that  direc- 
tions symmetrical  with  respect  to  the  median  plane  of  the 


THE  ANALYSIS  OF  SENSATIONS        115 

head  excite  similar  space-sensations,  it  becomes  easy  to 
understand  the  above-mentioned  facts.  The  straight  line 
has,  in  all  its  elements,  the  same  direction,  and  everywhere 
excites  the  same  space-sensations.  Herein  consists  its 
aesthetic  value.  Moreover,  straight  lines  which  lie  in  the 
median  plane  or  are  perpendicular  to  it  are  brought  into 
special  relief  by  the  circumstance  that,  thanks  to  this 
position  of  symmetry,  they  stand  in  the  same  relation  to 
both  of  the  two  halves  of  the  visual  apparatus.  Every  other 
position  of  the  straight  line  is  felt  as  an  obliquity,  as  a 
deviation  from  the  position  of  symmetry. 

The  repetition  of  the  same  space-figure  in  the  same  posi- 
tion conditions  a  repetition  of  the  same  space-sensation. 
All  lines  connecting  prominent  (noticeable)  homologous 
points  have  the  same  direction  and  excite  the  same  sensa- 
tion. Likewise  when  merely  geometrically  similar  figures 
are  placed  side  by  side  in  the  same  positions,  this  relation 
holds.  The  sameness  of  the  dimensions  alone  is  absent. 
But  when  the  positions  are  disturbed,  this  relation,  and 
with  it,  the  impression  of  unity — the  aesthetic  impression — 
are  also  disturbed. 

In  a  figure  symmetrical  with  respect  to  the  median  plane, 
similar  space-sensations  corresponding  to  the  symmetrical 
directions  take  the  place  of  the  identical  space-sensations. 
The  right  half  of  the  figure  stands  in  the  same  relation  to 
the  right  half  of  the  visual  apparatus  as  the  left  half  of 
the  figure  does  to  the  left  half  of  the  visual  apparatus. 
If  we  alter  the  sameness  of  the  dimensions,  the  sensa- 
tion of  symmetrical  similarity  is  still  felt.  An  oblique 
position  of  the  plane  of  symmetry  upsets  the  whole 
relation. 


n6        THE  ANALYSIS  OF  SENSATIONS 

If  we  turn  a  figure  through  180°,  contrasting  it  with 
itself  in  its  original  position,  centric  symmetry  is  produced. 
That  is,  if  two  pairs  of  homologous  points  be  connected, 
the  connecting  lines  will  cut  each  other  at  a  point  <9, 
through  which,  as  their  point  of  bisection,  all  lines  connect- 
ing homologous  points  will  pass.  Moreover,  in  the  case 
of  centric  symmetry,  all  lines  of  connexion  between  homo- 
logous points  have  the  same  direction, — a  fact  which 
produces  an  agreeable  sensation.  If  the  sameness  of  the 
dimensions  is  eliminated,  there  still  remains,  for  sensation, 
centrically  symmetrical  similarity. 

Regularity  appears  to  have  no  special  physiological  value, 
in  distinction  from  symmetry.  The  value  of  regularity 
probably  lies  only  in  its  manifold  symmetry,  which  is 
perceptible  in  more  than  one  single  position. 


12. 

The  correctness  of  these  observations  will  be  apparent 
on  glancing  over  the  work  of  Owen  Jones — A  Grammar  of 
Ornament^  London,  1865.  In  almost  every  plate  one 
finds  new  and  different  kinds  of  symmetry  as  fresh  testi- 
mony in  favor  of  the  conceptions  above  advanced.  The 
art  of  decoration,  which,  like  pure  instrumental  music,  aims 
at  no  ulterior  end,  but  ministers  only  to  pleasure  in  form 
and  color,  is  the  best  source  of  material  for  our  present 
studies.  Writing  is  governed  by  other  considerations  than 
that  of  beauty.  Nevertheless,  we  find  among  the  twenty- 
four  large  Latin  letters  ten  which  are  vertically  symmetrical 
(A,  H,  I,  M,  O,  T,  V,  W,  X,  Y),  five  which  are  horizon- 
tally symmetrical  (B,  C,  D,  E,  K),  three  which  are  centri- 


THE  ANALYSIS  OF  SENSATIONS        117 

cally   symmetrical   (N,    S,   Z),   and    only   six    which    are 
unsymmetrical  (F,  G,  L,  P,  Q,  R). 

The  study  of  the  evolution  of  primitive  art  is  extremely 
instructive  in  connexion  with  the  problems  under  discussion. 
The  character  of  primitive  art  is  determined,  firstly,  by 
the  natural  objects  that  offer  themselves  to  the  imitation 
of  the  artist  j  secondly,  by  the  degree  of  mechanical  skill 
attained  ;  and  finally  by  the  effort  to  make  use  of  repetition 
in  its  various  forms.1 


I  have  clearly  explained  briefly  in  previous  writings  the 
aesthetic  significance  of  the  above-mentioned  facts,  to  treat 
of  which  in  detail  was  not  part  of  my  plan.  I  cannot,  how- 
ever, refrain  from  mentioning  that  this  has  been  done  by  a 
physicist,  the  late  J.  L.  Soret  of  Geneva,  in  an  admirable 
book  published  in  1892,2  for  which  the  way  was  prepared 
by  a  lecture  delivered  by  him  at  the  meeting  of  the  Swiss 
Scientific  Association  in  1866.  Soret's  views  are  connected 
with  those  of  Helmholtz,  and  he  does  not  seem  to  be 
acquainted  with  my  theories.  He  does  not  go  into  the 
physiological  side  of  the  question,  but  on  the  aesthetic  side 
his  exposition  is  very  copious  and  illustrated  by  appropriate 
examples.  He  discusses  the  aesthetic  effect  of  symmetry,  of 
repetition,  of  similarity  and  of  continuity,  which  last  he 
regards  as  a  special  case  of  repetition.  According  to  him 
slight  deviations  from  symmetry  can  more  than  compensate 

1  Alfred  C.  Haddon,  Evolution  in  Art,  as  illustrated  by  the  Life- 
histories  of  Designs  ;  London,  1895. 

2  J.  L.  Soret,  Sur  les  conditions  physiques  de  la  perception  du  bcatt, 
Geneva,  1892. 


n8        THE  ANALYSIS  OF  SENSATIONS 

for  the  loss  in  sensual  satisfaction  by  the  multiplicity  which 
they  introduce  and  by  the  intellectual  aesthetic  pleasure 
bound  up  with  that  multiplicity.  This  is  illustrated  from 
the  sculptured  ornaments  of  Gothic  cathedrals.  This 
intellectual  pleasure  is  also  produced  by  the  virtual  or 
potential  symmetry  which  we  perceive  when  the  human 
figure  or  some  other  symmetrical  form  is  placed  in  an 
asymmetrical  position.  And  he  does  not  merely  apply 
these  reflexions  to  optical  cases,  but  extends  them  to  all 
departments,  as  also  has  been  done  by  me.  He  notices 
rhythm,  music,  movements,  dancing,  the  beauties  of  Nature, 
and  even  literature.  Particularly  interesting  are  his 
observations  on  blind  people,  which  the  Asylum  for  the 
Blind  at  Lausanne  gave  him  the  opportunity  of  carrying  out. 
Blind  people  take  pleasure  in  the  periodic  repetition  of  the 
same  forms  in  tangible  objects,  and  have  a  decided  sense 
of  formal  symmetry.  Striking  disturbances  in  symmetry  of 
form  are  unpleasant  to  them,  and  sometimes  even  seem  to 
them  ludicrous.  A  blind  man,  who  had  been  accustomed 
to  study  a  large-scale  map  of  Europe  in  relief,  recognized 
that  continent  by  means  of  geometrical  similarity  when  he 
found  it  as  part  of  a  larger  raised  map  on  a  smaller  scale. 
The  symmetrical  organs  of  touch,  the  two  arms  and  hands, 
are  in  fact  arranged  in  an  analogous  way  to  the  organs  of 
sight,  so  that  we  need  not  be  surprised  at  the  agreement. 
Even  in  antiquity  this  agreement  was  not  without  its 
influence  upon  inquirers,  to  say  nothing  of  a  modern 
thinker  like  Descartes;  it  even  produced  a  number  of 
unfortunate  notions  which  are  partly  operative  even  to-day. 
Soret's  chapter  on  literature  seems  less  successful.  True, 
in  metre,  rhyme,  etc.,  we  have  phenomena  similar  to  those 


THE  ANALYSIS  OF  SENSATIONS        119 

noticed  in  the  previously  treated  departments.  But  when, 
for  example,  he  draws  a  parallel  between  the  effect  of  the 
sixfold  repetition  of  the  phrase  "  Que  diable  allait  il  faire 
dans  cette  galere,"  in  Moliere's  well-known  play,1  and  the 
repetition  of  an  ornamental  motive,  probably  few  will  agree 
with  him.  It  is  certain  that  the  effect  of  this  repetition  is 
not  produced  by  the  repetition  as  such,  but  by  the  succes- 
sive heightening  of  a  comic  contrast,  and  that  consequently 
it  is  merely  intellectual. 

Finally,  I  should  like  to  draw  the  attention  of  the  reader 
to  an  article  by  Arnold  Emch  in  The  Monist  for  October, 
1900,  on  "Mathematical  Principles  of  ^Esthetic  Forms." 
Emch  gives  attractive  examples  of  the  way  in  which  a 
number  of  forms  arranged  in  a  series  co-operate  to  produce 
an  aesthetic  impression  by  observing  one  and  the  same 
geometrical  principle.  He  is  following  out  the  line  of 
thought  on  which  I  touched  in  my  lecture  of  1871,  accord- 
ing to  which  production  in  accordance  with  a  fixed  rule 
has  an  aesthetic  effect  (Popular  Scientific  Lectures,  Chicago, 
Open  Court  Publishing  Co.,  1894).  But  in  that  place  I 
laid  stress  upon  the  point,  and  should  like  to  do  so  again, 
that  the  rule,  considered  as  an  affair  of  the  intellect,  has  no 
aesthetic  effect  in  itself,  but  that  the  effect  depends  on  the 
repetition,  determined  by  the  rule,  of  one  and  the  same 
sensational  motive. 

14. 

Here  we  must  once  more  point  out  that  the  geometrical 
and.  the  physiological  properties  of  a  figure  in  space  are  to  be 

1  Les  Fotirberies  de  Scapin. 


120        THE  ANALYSIS  OF  SENSATIONS 

sharply  distinguished.  The  physiological  properties  are 
determined  by  the  geometrical  properties  coincidently  with 
these,  but  are  not  determined  by  these  solely.  On  the 
other  hand,  physiological  properties  very  probably  gave 
the  first  impulse  to  geometrical  investigations.  The 
straight  line  doubtless  first  attracted  attention  not  because 
of  its  being  the  shortest  line  between  two  points,  but 
because  of  its  physiological  simplicity.  The  plane  likewise 
possesses,  in  addition  to  its  geometrical  properties,  a  special 
physiologico-optical  (aesthetic)  value,  which  causes  it  to  be 
noticed,  as  will  be  shown  later  on.  The  division  of  the 
plane  and  of  space  by  right  angles  has  not  only  the 
advantage  of  producing  equal  parts,  but  also  an  additional 
and  special  symmetry-value.  The  circumstance  that 
congruent  and  similar  geometrical  figures  can  be  brought 
into  positions  where  their  relationship  is  physiologically 
felt,  led,  no  doubt,  to  an  earlier  investigation  of  these 
kinds  of  geometrical  relationship  than  of  those  that  are  less 
noticeable,  such  as  affinity,  collineation,  and  others.  With- 
out the  co-operation  of  sense-perception  and  understanding, 
'a  scientific  geometry  is  inconceivable.  But  H.  Hankel 
has  admirably  shewn  in  his  History  of  Mathematics  (Leipzig, 
1874)  that  in  Greek  geometry  the  factor  of  pure  under- 
standing is  decidedly  dominant,  whereas  in  Indian  geometry 
the  factor  of  sense  has  the  upper  hand.  The  Hindus 
make  use  of  the  principles  of  symmetry  and  similarity  (see, 
for  example,  p.  206  of  Hankel's  book)  with  a  generality 
which  is  totally  foreign  to  the  Greeks.  Hankel's  proposal 
to  unite  the  rigor  of  the  Greek  method  with  the  perspicuity 
of  the  Indian  in  a  new  mode  of  presentation  is  well  worthy 
of  encouragement.  Furthermore,  in  so  doing,  we  should 


THE  ANALYSIS  OF  SENSATIONS        121 

only  be  following  in  the  footsteps  of  Newton  and  John 
Bernoulli,  who,  even  in  mechanics,  applied  the  principle  of 
similarity  in  a  still  more  general  manner.  The  advantages 
that  the  principle  of  symmetry  affords  in  the  last-named 
department,  I  have  shown  at  length  elsewhere.1 

1  I  have  given  less  complete  discussions  of  the  leading  thoughts  of 
this  chapter  in  the  paper  already  mentioned,  Ueberdas  Sehen  von  Lagen 
und  Winkeln  (1861),  further  (in  Fichte's  Zeitschrift  fur  Philosophic, 
Vol.  XLVL,  1865,  p.  5,  and  in  The  Forms  of  Liquids,  and  Symmetry 
(1872)  now  also  published  in  my  Popular  Scientific  Lectures,  translated 
by  Thomas  J.  McCormack,  Open  Court  Publishing  Co., Chicago,  1894. 
With  regard  to  the  use  of  the  principle  of  symmetry  in  mechanics, 
compare  my  work  The  Science  of  Mechanics  (1883),  translated  by 
Thomas  J.  McCormack,  1893,  Open  Court  Pub.  Co.,  Chicago. 


VII.    FURTHER  INVESTIGATION  OF 
SPACE-SENSATIONS.1 


i. 

OUR  knowledge  of  spatial  vision  made  important 
advances  in  the  course  of  the  nineteenth  century,  not 
merely  because  a  gain  in  positive  understanding  was 
involved,  but  also  because  the  prejudices  accumulated 
by  various  philosophers  and  physicists  in  this  department, 
especially  since  Descartes,  have  been  finally  disposed  of, 
and  thereby  that  freedom  from  preconceptions  attained 
which  is  the  first  requisite  for  making  positive  discoveries. 

Johannes  Miiller,2  created  the  doctrine  of  specific 
energies,  and  also  put  forward  with  great  lucidity  the 
theory  of  identical  retinal  positions,  which,  for  the  rest, 
can  be  clearly  traced  back  as  far  as  Ptolemy.3  On  Miiller's 

1  So  far  as  I  know,  the  matter  treated  in  the  preceding  chapter  has 
not  yet  been  discussed,  except  in  three  small  works  of  my  own,  and  in 
Soret's  book.     The  considerations  of  the  present  chapter,  moreover, 
are,  for  me,  founded  upon  those  of  the  preceding  chapter.     I  indicate 
here  the  methods  by  which  I  have  myself  reached  clear  ideas  as  to  the 
sensation  of  space,  without  laying  the  least  claim  to  that  which  has 
been  accomplished  by  others  in  this  direction,  particularly  by  the  theory 
of  Hering.     The  extensive  literature  of  this  subject  is,  moreover,  too 
imperfectly  known  to  me  for  me  to  give  exact  references  on  all  points. 
The  point  of  Hering's  theory  which  I  regard  as  the  most  important  I 
will  especially  notice. 

2  J.    Miiller,    Vergleichende    Physiologic    des    Gesichtsinnes,    1826; 
Handbuch  der  Physiologic,  Vol.,  II.,  1840. 

3  L'Ottica  di  Claudio  Tolomeo,  published  by  G.  Govi,  Turin,  1885. 

122 


THE  ANALYSIS  OF  SENSATIONS        123 

theory  that  the  retina  has  sensations  of  itself  in  its  own 
activity,  "visual  space"  is,  for  him,  something  immediately 
given.  My  own  body  also  appears  in  my  field  of  vision. 
All  questions  of  direction  can  only  refer  to  the  relative 
positions  of  parts  of  the  field  of  vision.  The  direc- 
tion of  vision  depends  exclusively  on  the  arrangement 
of  the  sensitive  parts  of  the  retina.  All  theories  as  to 
projection,  and  problems  as  to  why  we  see  things  upright, 
disappear.  But  estimation  of  the  distance  of  an  object 
seen  is,  for  Miiller,  still  through  and  through  an  affair  of 
the  intellect. 

Wheatstone's  1  discovery  of  the  spectroscope  led  at  once 
to  the  conviction  that  in  certain  circumstances  images 
could  be  seen  as  simple,  and  with  different  degrees  of  depth 
according  to  the  stereoscopic  difference,  not  only  when  the 
images  fell  upon  identical  parts  of  the  retina,  but  also  when 
they  fell  upon  other  parts,  provided  the  difference  between 
the  parts  was  not  too  great.  The  result  of  this  was  to  throw 
doubt  on  the  doctrine  of  identity,  and  to  stimulate  the 
formulation  of  psychological  explanations  of  how  we  come 
to  see  things  as  having  depth.  Hence  arose  Briicke's 
theory  of  successive  fixation  in  spatial  vision,  which  in  its 
turn  was  proved  to  be  untenable  by  Dove's  experiments  in 
instantaneous  illumination  with  the  stereoscope. 

Panum  2  opposed  these  theories  with  arguments  of  great 
force,  and  by  admirably  contrived  experiments.  Taking  his 
stand  on  the  phenomenon  of  binocular  rivalry  and  the 
prominent  part  played  therein  by  contours,  he  came  to  the 

1  Wheatstone,  "  Contributions  to  the  Theory  of  Vision,"  Philosophical 
Transactions  1838,  1852. 

2  Panum,  Untersuchungen  liber  das  Sehen  mit  zwei  Augen,  1858. 


124        THE  ANALYSIS  OF  SENSATIONS 

conclusion  that  our  seeing  things  as  having  depth  depends 
upon  a  reciprocal  action,  or  "  Synergy/'  of  the  two  retinae, 
and  that  the  sensation  of  depth  is  an  innate  specific  energy. 
The  more  similar  the  two  monocular  images,  and  especially 
the  contours,  are  in  form,  color,  and  position,  the  more 
easily  do  they  coalesce  into  a  single  binocular  image,  of 
which  the  depth  is  determined  by  the  stereoscopic 
difference.  But  Panum  still  maintains  that  this  depth 
corresponds  to  what  is  given  by  means  of  lines  of 
projection. 

It  is  to  Hering  *  that  we  owe  the  most  thorough  clearing 
away  of  old  prejudices.  His  starting-point  is  the  view  that 
our  immediately  given  visual  space  must  be  completely  dis- 
tinguished from  the  conceptual  space  which  we  obtain  by 
means  of  experiences  of  a  special  kind.  He  proves  by 
decisive  experiments  that  the  direction  in  which  we  see  an 
object  is  different  from  the  line,  — the  line  of  vision,  or  of 
projection,- — between  the  object  and  the  retinal  image. 
There  are  two  lines  of  vision,  one  for  each  eye  ;  but  there 
is  only  one  direction  of  vision,  bisecting  the  angle  formed 
by  these  two  lines.  We  have  to  think  of  this  direction  of 
vision  as  proceeding  from  the  point  of  bisection  of  the 
line  connecting  the  two  eyes.  In  order  to  exclude  all 
reference  to  geometrical  space,  we  may  put  it  thus  :  The 
two  eyes  together  see  the  same  relative  horizontal  and 
perpendicular  arrangements  that  a  single  eye  would  see 
if  it  were  situated  half-way  between  the  two  eyes.  Suppose 
that,  looking  in  a  horizontal  direction  and  with  symmetrical 

1  Hering,  Beitrdge  zur  Physiologic,  1861-1865  ;  Archivfar  Anatomie 
und  Physiologic,  1864,  1865  ;  "  Der  Raumsinn  und  die  Bewegungen  des 
Auges,"  in  Hermann's  Handbuch  der  Physiologic,  Vol.  III.,  I,  1879. 


THE  ANALYSIS  OF  SENSATIONS        125 

convergence,  we  fix  our  gaze  upon  a  point  on  the  window- 
pane  ;  then  we  see  this  point  in  the  median  plane,  but  at 
the  same  time  we  see  behind  it  in  the  same  plane  objects 
lying  a  long  way  to  one  side.  In  the  stereoptical  experi- 
ment we  still  see  objects  in  front  of  us,  even  when  there  is 
only  a  slight  divergence  of  the  axes  of  the  eyes,  although  the 
directions  of  projection  no  longer  lead  to  these  objects,  or 
at  any  rate  have  no  longer  any  physical  or  physiological 
meaning.  Again,  the  distances  which  we  see  do  not  agree 
with  the  results  of  the  theory  of  projection.  When,  with 
horizontal  lines  of  vision,  we  stretch  vertical  threads  through 
Miiller's  circular  horopter,  the  cylinder  thereby  produced 
appears  to  us  like  a  plane.  We  see  not  only  the  image  of 
the  fixed  or  "nucleus"  point,  but  also  the  collective  con- 
ception of  all  the  points  (the  "  nucleus-surface  ")  represented 
in  identical,  or  "corresponding,"  positions,  as  a  plane  lying 
before  us  at  a  definite  distance.  It  is  impossible  to  explain 
these  and  many  other  analogous  facts  on  the  theory  of 
projection.  Hering  reduces  spatial  vision  to  a  simple 
principle.  Identical,  or  "corresponding,"  points  on  the 
retina  have  identical  height  and  breadth-values ;  symmetri- 
cal points  on  the  retina,  on  the  other  hand,  have  identical 
depth-values,  and  these  last  increase  from  the  outer  edges 
of  the  retina  inwards.  When  similarity  of  the  monocular 
images  in  color,  shape  and  position  causes  them  to  coalesce 
into  a  singular  binocular  image,  the  binocular  image  con- 
tains the  mean  value  of  the  depth-values  of  the  single 
images.  Such  mean  values  of  the  single  images  play  a 
decisive  part  in  general,  and  in  particular  as  regards  the 
directions  of  vision.  These  indications  must  be  sufficient 
for  us  here,  since  we  cannot  now  discuss  in  detail  the  varied 


126        THE  ANALYSIS  OF  SENSATIONS 

contents  of  the  works  in  which  Hering  has  laid  the  secure 
foundations  on  which  this  chapter  is  based.1  The  only 
further  remark  I  will  make  is,  that,  according  to  him,  the 
two  eyes  are  to  be  conceived  as  a  single  united  organ,  the 
associated  movements  of  which  rest  on  an  innate  anatomical 
foundation, — a  point  that  had  already  been  brought  out 
by  Johannes  Miiller. 

Biological  and  psychological 2  research  combine  to  con- 
firm the  conclusion  that,  as  regards  the  intuition  of 
space,  the  nativistic  view  can  a  fortiori  be  maintained. 
The  chick  has  scarcely  broken  from  its  shell  than  it  is 
seen  to  be  at  home  in  space  and  pecking  at  everything 
that  excites  its  attention.  For  the  new-born  human  being 
we  can  at  most  suppose  only  a  lower  degree  of  maturity, 
but  otherwise  the  conditions  must  be  essentially  the  same. 
Panum  has  brought  out  this  point.  Spatial  intuition 
is  therefore  present  at  birth.  Whether  we  shall  ever  be 
in  a  position  to  explain  it,  in  the  sort  of  way  attempted 
by  Helmholtz,  by  means  of  the  history  of  evolution  or  the 
history  of  the  race,  is  a  separate  question. 

Perhaps  clues  towards  the  solution  of  this  problem 
may  be  found  in  the  facts  of  phylogenetic  develop- 
ment and  the  variation  of  retinal  correspondence 
(investigated  by  Johannes  Miiller 3)  which  takes  place 
at  the  transition  between  one  animal  species  and 
another.  Another  promising  field  for  research  is  pre- 


1  Among  the  works  of  younger  investigators  connected  with  Hering's 
researches,    those   of    F.    Hillebrand    are    of    particular   interest  for 
psychology. 

2  Stumpf  Der  psychologische  Urspwng  der  Raumvorstellungen,  1873. 

3  Vergleichende  Physiologic  des  Gesichtssinnes,  pp.  106,  sqq. 


THE  ANALYSIS  OF  SENSATIONS        127 

sented  by  the  pathological  anomalies  of  people  who 
squint  and  the  phenomena  of  adaptation  to  be  observed 
in  these  cases.1 


2. 

That  space-sensation  is  connected  with  motor  processes 
has  long  since  ceased  to  be  disputed.  Opinions  differ  only 
as  to  how  this  connexion  is  to  be  understood. 

If  two  congruent  images  of  different  colors  fall  in 
succession  on  the  same  parts  of  the  retina,  they  are  at  once 
recognized  as  identical  figures.  We  may,  therefore,  regard 
different  space-sensations  as  connected  with  different  parts 
of  the  retina.  But  that  these  space-sensations  are  not 
unalterably  connected  with  particular  parts  of  the  retina, 
we  perceive  on  moving  our  eyes  freely  and  voluntarily, 
whereby  the  objects  observed  do  not  change  their  position 
or  form,  although  their  images  are  displaced  on  the  retina. 

If  I  look  straight  before  me,  fixing  my  eyes  upon   an 
object  O,  an  object  A,  which  is  re- 
flected on  the  retina  in  a,  at  a  certain 
distance   below  the   point   of  most 
distinct  vision,  appears  to  me  to  be 

situated  at  a  certain  height.     If  I 

,  .  Fig.  15- 

now  raise  my  eyes,  fixing  them  upon 

B,  A  retains  its  former  height.     It  would  necessarily  appear 

1  Tschermak,  '  *  Ueber  anomale  Sehrichtungsgemeinschaft  der 
Netzhaute  bei  Schielenden,"  Graefe's  Archiv,  XLVIL,  3,  p.  508  ; 
Tschermak,  Ueber  physiologische  und  pathologischc  Anpass^^ng  des 
Auges,  Leipzig,  1900;  Schlodtmann,  "  Studien  iiber  anomale 
Sehrichtungsgemeinschaft  bei  Schielenden,"  Graefe's  Archiv, 
LI-,  2,  1900. 


128        THE  ANALYSIS  OF  SENSATIONS 

lower  down  if  the  position  of  the  image  on  the  retina,  or  the 
arc  0a,  alone  determined  the  space-sensation.  I  can  raise  my 
glance  as  far  as  A  and  farther  without  any  change  in  this 
relation.  Thus,  the  physiological  process  which  conditions 
the  voluntary  raising  of  the  eye,  can  entirely  or  partly  take 
the  place  of  the  height-sensation,  is  homogeneous  with  it, 
or,  in  brief,  algebraically  summable  with  it.  If  I  turn  my 
eyeball  upward  by  a  slight  pressure  of  the  finger,  the 
object  A  actually  appears  to  sink,  proportionately  to  the 
shortening  of  the  arc  oa.  The  same  thing  happens  when, 
by  any  other  unconscious  or  involuntary  process — for 
example,  through  a  cramp  of  the  muscles  of  the  eye — the 
eyeball  is  turned  upward.  According  to  an  experience  now 
familiar  to  oculists  for  some  decades  patients  with  paralysis 
of  the  rectus  externus  reach  too  far  to  the  right  in  attempt- 
ing to  grasp  objects  at  the  right.  Since  they  need  to  exert 
a  stronger  impulse  of  the  will  than  persons  of  sound  eyes, 
in  order  to  fix  their  glance  upon  an  object  to  the  right, 
the  thought  naturally  suggests  itself  that  the  will  to  look 
to  the  right  determines  the  optical  space-sensation  "right." 
Some  years  ago,1  I  put  this  observation  into  the  form  of 
an  experiment,  which  every  one  can  try  for  himself.  Let 
the  eyes  be  turned  as  Jar  as  possible  towards  the  left  and 
two  large  lumps  of  moderately  hard  putty  firmly  pressed 
against  the  right  side  of  each  eye-ball.  If,  now,  we  attempt 
to  glance  quickly  to  the  right,  we  shall  succeed  only  very 
imperfectly,  owing  to  the  imperfectly  spherical  form  of  the 
eyes,  and  the  objects  will  suffer  a  strong  displacement  to 
the  right.  Thus  the  mere  will  to  look  to  the  right  imparts 

1  Shortly  after  finishing  my  Grundlinien  der  Lehre  von  den  Beweg- 
ungsempfindungen  (1875). 


THE  ANALYSIS  OF  SENSATIONS        129 

to  the  images  at  certain  points  of  the  retina  a  larger  "  right- 
ward  value,"  as  we  may  term  it  for  brevity.  The  experiment 
is,  at  first,  surprising.  It  will  soon  be  perceived,  however,  that 
both  facts — viz.,  that  by  voluntarily  turning  the  eyes  to  the 
right,  objects  are  not  displaced,  and  that  by  the  forced,  in- 
voluntary turning  of  the  eyes  to  the  left,  objects  are  displaced 
to  the  right — together  teach  the  same  lesson.  My  eye,  which 
I  wish  to,  and  cannot,  turn  to  the  right,  may  be  regarded  as 
voluntarily  turned  to  the  right  and  compulsorily  turned  back 
by  an  external  force.  Professor  W.  James  l  could  not  get 
the  experiment  just  mentioned  to  succeed.  I  have  often  re- 
peated it,  and  always  found  it  confirmed.  I  think  that  the 
fact  is  certain,  but  of  course  that  decides  nothing  as  to  its 
correct  interpretation. 

3- 

The  will  to  perform  movements  of  the  eyes,  or  the 
innervation  to  the  act,  is  itself  the  space-sensation.  This 
follows  naturally  from  the  preceding  consideration.2  If  we 
have  a  sensation  of  itching  or  pricking  in  a  certain  spot  of 
our  skin,  by  which  our  attention  is  sufficiently  secured,  we 
immediately  grasp  at  the  spot  with  the  correct  amount  of 
movement.  In  the  same  manner  we  turn  our  eyes  with 
the  correct  amount  of  exertion  towards  an  object  reflected 
on  the  retina,  as  soon  as  this  exerts  a  sufficient  stimulus  to 
draw  our  attention.  By  virtue  of  organic  arrangements 
and  long  exercise  we  hit  immediately  upon  the  exact 

1  W.  James,  The  Principles  of  Psychology,  II.,  p.  509. 

2 1  retain  the  expression  which  first  immediately  suggested  itself  to 
me  (1875),  with  no  intention  of  forestalling  future  inquiry.  Here  and  in 
what  follows  I  leave  it  an  open  question  whether  innervation  is  a  con- 
sequence of  space-sensation,  or  vice  versa.  They  are  certainly  closely 
connected. 


130        THE  ANALYSIS  OF  SENSATIONS 

degree  of  innervation  sufficient  to  enable  us  to  fix  our 
eyes  upon  an  object  reflected  on  a  certain  point  of  the 
retina.  If  the  eyes  are  already  turned  towards  the  right, 
and  we  begin  to  give  our  attention  to  an  object  further  to 
the  right  or  the  left,  a  new  innervation  of  the  same  sort  is 
algebraically  added  to  that  already  present.  A  disturbance 
of  the  process  arises  only  when  alien,  involuntary  innerva- 
tions  or  externally  moving  forces  are  added  to  the  innerva- 
tions  determined  by  the  will. 


Years  ago,  while  occupied  with  the  questions  now  under 
discussion,  I   noticed  a  peculiar  phenomenon,  which  has 

not  yet,  so  far  as  I  know, 
been  described.  In  a 
very  dark  room  we  fix 
our  eyes  upon  a  light 
A,  and  then  suddenly 
look  at  a  light  lower 
down,  B.  At  this,  the 
light  A  appears  to  make 
a  rapid  sweep  A  A' 
(quickly  ended)  up- 
wards. The  light  B,  of  course,  does  the  same ;  but  to  avoid 
complications,  this  is  not  indicated  in  the  diagram.  The 
sweep  is,  of  course,  an  after-image,  which  enters  conscious- 
ness only  on  completion,  or  shortly  before  completion,  of  the 
glance-movement,  but — and  this  is  the  remarkable  point — 
with  positional  values  that  correspond,  not  to  the  later, 
but  to  the  earlier  innervations  and  position  of  the  eye. 
Similar  phenomena  are  often  noticed  in  experiments  with 


THE  ANALYSIS  OF  SENSATIONS        131 

Holtz's  electrical  machine.  If  the  experimenter  is  surprised 
by  a  spark  during  a  glance  downwards,  the  spark  often 
appears  high  above  the  electrodes.  If  it  yields  a  lasting 
after-image,  the  image  appears,  of  course,  below  the 
electrodes.  The  preceding  phenomena  answer  to  the  so- 
called  personal  equation  of  astronomers,  except  that  they 
are  confined  to  the  province  of  sight.  By  what  organic 
arrangements  this  relation  is  determined  must  be  left  an 
open  question,  but  it  is  probably  of  some  value  in  pre- 
venting confusion  of  position  in  movements  of  the  eyes.1 


For  the  sake  of  simplicity  we  have  hitherto  regarded 
only  the  eyes  as  in  motion,  and  have  considered  the  head 
and  the  body  generally  as  at  rest.  If,  now,  we  move  the 
head  about  without  intentionally  fixing  the  eyes  upon  any 
object,  the  objects  seen  remain  motionless.  But  at  the 
same  time  another  observer  may  notice  that  the  eyes,  like 
frictionless,  inert  masses,  take  no 
part  in  the  turning  movements. 
Still  more  noticeable  is  the  pheno. 
menon  if  we  turn  with  continuous 
motion,  actively  or  passively,  about  a 
vertical  axis,  as  viewed  from  above, 

say,  in  the  direction  of  the  hands  of  a  clock.  In  this  case,  as 
Breuer  has  observed,  the  open  or  closed  eyes  turn,  about 
ten  times  to  a  full  revolution  of  the  body,  in  the  opposite 
direction  to  that  of  the  clock-hands,  with  a  uniform 
motion,  and  as  frequently  back  again  in  the  opposite 

1  For  a  different  explanation  see  Lipps,  Zcitschrift  fur  Psychologic 
Tind  Physiologic  der  Sinnesorgane^  Vol.  I.,  p.  60. 


132        THE  ANALYSIS  OF  SENSATIONS 

direction  by  jerks.  The  process  is  represented  in  the 
diagram  of  Fig.  17.  On  O  T,  the  times  are  laid  off  as 
abscissae,  the  angles  described  in  the  direction  of  the 
clock-hands  are  laid  off  as  ordinates  upwards,  and  the 
angles  described  in  the  opposite  direction  as  ordinates 
downwards.  Tne  curve  OA  corresponds  to  the  rotation 
of  the  body,  O  B  B  to  the  relative,  and  O  C  C  to  the 
absolute,  rotation  of  the  eyes.  No  one,  on  repeating  the 
experiment,  can  avoid  the  conclusion  that  we  are  concerned 
here  with  an  automatic  (unconscious)  movement  of  the 
eyes,  reflexively  excited  by  the  rotation  of  the  body.  This 
movement  disappears  as  soon  as  the  passive  rotation  is  no 
longer  felt.  How  it  is  brought  about  remains,  naturally,  to 
be  investigated.  A  simple  way  of  looking  at  it  would  be  that 
there  are  two  antagonistic  organs  of  innervation,  and  that  the 
stimulus  which  reaches  them  both  uniformly  when  the  body 
rotates,  is  answered  by  one  with  a  uniform  stream  of 
innervation,  while  the  other  delivers  its  impulse  of  innerva- 
tion only  after  the  lapse  of  a  certain  time,  like  a  rain-gauge 
suddenly  tipping  up  when  it  is  full.  For  us  it  suffices, 
provisionally,  to  know  that  this  automatic,  unconscious 
compensational  movement  of  the  eye  is  actually  present. 

The  compensational  wheel-like  movement  of  the  eyes, 
which  takes  place  when  the  head  is  inclined  to  one  side,  is 
well-known.  Nagel *  has  proved  that  it  amounts  to  from 
one-tenth  to  one-sixth  of  the  angle  of  inclination  of  the 
head.  And  recently  Breuer  and  Kreidl 2  have  made  similar 

1  Nagel,  "  Ueber  Kompensatorische  Raddrehungen  der  Augen,"  Zeit- 
schriftfurPsychologieundPhysiologie  der Sinnesorgane,  Vol.  XII. ,  p.  338. 

2  Breuer  and  Kreidl,  "  Ueber  scheinbare  Drehung  des  Gesichtsfeldes 
wahrend   der  Einwirkung  einer  Zentrifugalkraft,"    Pfltiger's  Archiv, 
Vol.  LXX.,  p.  494- 


THE  ANALYSIS  OF  SENSATIONS        133 

experiments  in  the  rotatory  apparatus  also,  with  the  follow- 
ing results : 

"  We  have  a  sensation,  as  Purkynie  and  Mach  have 
maintained,  of  the  direction  of  the  acceleration  of  masses. 
When  this  direction  is  changed  by  the  interference  of  a 
horizontal  acceleration  affecting  the  body  on  one  side,  a 
wheel-like  movement  of  the  eyes  is  set  up  and  persists  as 
long  as  the  interference  lasts.  It  amounts  to  0-5  or  o'6  of 
the  angle  of  deviation.  The  rotation  of  visual  space,  and 
the  appearance  of  vertical  lines  as  oblique,  which  takes 
place  under  such  conditions,  depend  therefore  on  an  actual 
but  unconscious  rotation  of  the  eyes." 

I  must  also  mention  here  two  papers  by  Crum  Browne  J 
on  compensating  movements  of  the  eyes. 


6. 

The  slower  unconscious  compensating  movement  of  the 
eye  (the  jerking  movement  leaves  behind  it  no  optical 
impression)  is  thus  the  reason  why,  when  the  head  is  turned, 
objects  seem  to  retain  their  position — a  fact  which  is  very 
important  for  orientation.  If,  now,  in  turning  our  head,  we 
also  voluntarily  turn  the  eyes  in  the  same  direction,  fixing 
them  upon  one  object  after  another,  we  must  overcompen- 
sate  the  automatic,  involuntary  innervation  by  the  voluntary 
innervation.  We  need  the  same  innervation  as  if  the  whole 
angle  turned  through  were  described  by  the  eye  alone.  In 

1  Crum  Brown,  "  Note  on  Normal  Nystagmus/*  Proc.  of  the  Royal 
Society  of  Edinburgh,  4th  Feb.  1895:  "The  Relation  between  the 
Movements  of  the  Eye  and  the  Movements  of  the  Head,"  Robert  Boyle 
Lechtre,  I3th  May  1895. 


134        THE  ANALYSIS  OF  SENSATIONS 

this  way  is  explained  why,  when  we  turn  about,  the  whole 
optical  space  appears  to  us  a  continuum  and  not  an  aggre- 
gation of  fields  of  vision ;  and  why,  at  the  same  time,  the 
optical  objects  remain  stationary.  That  which  we  see  of 
our  own  body,  in  turning,  we  see,  for  obvious  reasons, 
optically  in  motion. 

Thus  we  arrive  at  the  practically  valuable  conception  of 
our  body  as  in  motion  in  a  fixed  space.  We  understand 
why  it  is  that,  in  our  numerous  turnings  and  ramblings  in 
the  streets  and  in  buildings,  and  in  our  passive  turnings  in 
a  wagon  or  in  the  cabin  of  a  ship,  even  in  the  dark,  we  do 
not  lose  our  sense  of  direction,  though  it  is  true  that  the 
primary  co-ordinates  from  which  we  started  gradually  sink 
unnoticed  into  unconsciousness,  and  we  soon  begin  to  reckon 
from  new  objects  around  us.  That  peculiar  state  of  con- 
fusion as  to  locality  in  which  we  sometimes  find  ourselves 
on  suddenly  awaking  at  night,  where  we  look  about  help- 
lessly for  the  window  or  the  table,  is  probably  due  to  dreams 
of  movement  immediately  preceding  our  awaking. 

Similar  phenomena  to  those  which  manifest  themselves  on 
the  rotation  of  the  body  make  their  appearance  in  connexion 
with  the  movements  of  the  body  generally.  If  I  move  my 
head  or  my  whole  body  sidewise,  I  do  not  lose  sight  of  an 
object  on  which  my  eyes  rest.  The  latter  seems  to  continue 
motionless,  while  the  more  distant  objects  undergo  a  dis- 
placement in  the  same  direction  as  that  of  the  body,  and  nearer 
objects  a  parallactic  displacement  in  the  opposite  direction. 
The  parallactic  displacements  to  which  we  are  accustomed  are 
perceived,  but  do  not  cause  us  any  disturbance  and  are  cor- 
rectly interpreted.  But  in  the  monocular  inversion  of  a  Plateau 
wire  -net,  the  parallactic  displacements,  which  in  the  present 


THE  ANALYSIS  OF  SENSATIONS        135 

case  are  unusual  as  regards  amount  and  direction,  immediately 
attract  the  eye,  and  apparently  present  to  us  a  revolving  object.1 


7- 

When  I  turn  my  head,  I  not  only  see  that  part  of  it  turn- 
ing which  I  am  able  to  see  (as  will  be  immediately  under- 
stood from  the  foregoing)  but  I  also  feel  it  turning.  This  is 
due  to  the  fact  that  conditions  exist  in  the  province  of  touch 
which  are  entirely  analogous  to  those  in  the  province  of  sight.2 

'Compare  my  "  Beobachtungen  liber  monoculare  Stereoscopic," 
Sitzungsberichte  der  Wiener  Akademie,  Vol.  LVIII.,  1868. 

2  The  view  that  the  sense  of  sight  and  the  sense  of  touch  involve,  so 
to  speak,  the  same  space-sense  as  a  common  element,  was  advanced 
by  Locke  and  contested  by  Berkeley.  Diderot  also  (Lettres  sur  les 
aveugles)  is  of  opinion  that  the  space-sense  of  the  blind  is  altogether 
different  from  that  of  a  person  who  sees.  Compare  on  this  point  the 
acute  remarks  of  Dr.  Th.  Loewy  ( Common  Sensibles.  Die  Gemeinideen 
des  Gesichts-  und  Tastsinnes  nach  Locke  und  Berkeley,  Leipzig,  1884), 
with  whose  results,  however,  I  cannot  agree.  The  circumstance  that 
a  man  blind  from  birth  does  not,  after  being  operated  upon,  in  accord- 
ance with  the  experiment  proposed  by  Molyneux,  visually  distinguish 
the  cubes  and  spheres  with  which  he  is  familiar  from  touch,  proves 
to  my  mind  nothing  at  all  against  Locke  and  nothing  in  favor  of 
Berkeley  and  Diderot.  Even  persons  who  see  recognize  figures 
that  are  turned  upside  down  only  after  much  practice.  The  fact 
is  that  at  the  first  moment  of  sight  all  the  associations  connected 
with  the  optical  process,  which  may  subserve  its  application  intel- 
lectually, are  wanting.  A  further  point  is  that,  when  optical 
stimuli  have  been  absent  for  a  long  period  in  early  youth,  the  develop- 
ment of  the  central  visual  spheres  may  be  arrested,  or  perhaps 
degeneration  may  even  take  place,  as  has  been  shewn  by  Schnabel's 
beautiful  observations  ("  Beitrage  zur  Lehre  von  der  Schlechtsichtig- 
keit  durch  Nichtgebrauch  der  Augen,"  Berichte  des  naturwissenschaft- 
lich-medikalischen  Vereins  in  Innsbruck,  Vol.  XI.,  p.  32),  and  by 
Munk's  experiments  on  new-born  puppies  (Berliner  klinische  Wochen- 
schrift,  1877,  No.  35).  Even  in  the  case  of  people  who  are  not 
actually  blind,  the  visual  sphere  may  be  so  little  developed  that  a 
special  education  is  required  to  enable  them  to  turn  their  sight-sensa- 


136        THE  ANALYSIS  OF  SENSATIONS 

When  I  reach  out  my  hand  to  grasp  an  object,  a  sensation 
of  touch  is  combined  with  an  innervation.  If  I  look  towards 

tions  to  account.  The  case  of  the  boy  described  by  S.  Heller,  the 
Director  of  the  Vienna  Institute  for  the  Blind  (  Wiener  klinische  Wochen- 
schrift,  25th  April  1901),  is  probably  such  a  case  of  partial  optical 
idiotism.  It  is  only  with  great  caution,  therefore,  that  conclusions 
should  be  drawn  from  the  behaviour,  after  operations,  of  those  born 
blind.  Chesselden,  for  instance,  gave  an  account  of  an  operation 
performed  on  a  man  blind  from  birth,  who  at  first  believed  that  every- 
thing he  saw  was  in  contact  with  his  eyes ;  from  this  the  false  conclusion 
was  drawn  that  the  perception  of  the  dimension  of  depth  depends  on 
extra-optical  experiences.  An  accident  put  me  in  the  way  of  under- 
standing this  phenomenon.  Once  when  I  was  walking  on  a  dark 
night  in  a  district  with  which  I  was  unfamiliar,  I  was  all  the  time 
afraid  of  running  up  against  a  large  black  object.  This  turned  out  to 
be  a  hill  several  kilometres  distant,  which  brought  about  this  pheno- 
menon through  my  being  unable  to  fix  and  accommodate  my  sight, 
in  much  the  same  way  as  people  who  have  been  newly  operated  must 
be  unabk  to  do.  If  any  one  is  not  convinced  by  his  own  stereoscopy 
that  the  dimension  of  depth  also  is  optically  given,  he  is  not  likely  to 
be  convinced  by  the  experiences  of  truncated  people  without  arms  and 
legs,  such  as  Eva  Lark  andKobelkoff(G.  Hirth,  Energische  Epigenesis, 
1898,  p.  165). 

All  systems  of  space-sensation,  however  different  they  may  be,  are 
connected  by  a  common  associative  link, — the  movements  which  they 
serve  to  guide.  If  Locke  was  wrong,  how  could  the  blind  Saunderson 
have  written  a  geometry  intelligible  to  those  who  are  not  blind  ? 
Without  doubt  there  are  analogies  between  the  sense  of  space  given 
through  sight  and  that  given  through  touch.  I  have  already  mentioned 
something  of  this  sort  in  discussing  Soret's  work  (p.  n 8,  above),  and 
many  of  these  phenomena  were  known  to  the  Aristotelian  school. 
Thus  in  the  Parva  Naturalia  we  find  mentioned  the  experiment  by 
which  a  little  ball  is  felt  as  double  when  touched  by  the  index-finger 
and  the  middle  finger  placed  across  it.  With  me  this  experiment 
produces  an  even  more  striking  effect  when  I  cross  my  fingers  and 
move  them  up  and  down  a  little  stick  ;  and  when  I  take  two  parallel 
sticks,  and  arranging  my  fingers  in  this  way.  run  them  between  them, 
I  feel  the  two  sticks  as  single.  The  analogy  with  seeing  the  single 
as  double  and  seeing  the  double  as  single  is  here  complete.  But  the 
differences  also  are  so  great  that  the  man  of  normal  sight  finds  it 
difficult  to  picture  to  himself  a  blind  man's  space-presentation,  since 


THE  ANALYSIS  OF  SENSATIONS        137 

the  object,  a  luminous  sensation  is  substituted  for  the  sen- 
sation of  touch.  Even  where  objects  are  not  touched,  skin- 
sensations  may  always  be  perceived  when  the  attention  is 
turned  to  them,  and  these,  combined  with  changing  inner- 
vations,  also  yield  the  conception  of  our  body  as  in  motion, 
which  quite  accords  with  that  acquired  by  optical  means. 

Thus,  in  active  movements,  the  skin-sensations  are 
delocalized,  as  we  may  briefly  express  it.  In  passive  move- 
ments of  the  body,  reflex,  unconscious  compensatory  innerva- 
tions  and  movements  of  compensation  make  their  appearance. 
In  turning  round  to  the  right,  for  example,  my  skin-sensations 
are  compounded  with  the  same  innervations  as  would  be 
combined  with  the  touching  of  objects  in  turning  to  the  right. 
I  feel  myself  turning  to  the  right.  If  I  am  passively  turned 
toward  the  right,  the  reflex  endeavour  arises  to  compensate 
the  turning.  I  either  actually  remain  stationary  and  feel 
myself  at  rest,  or  I  repress  the  motion  toward  the  left.  But 
for  this  I  need  to  exert  the  same  voluntary  innervation  as 
for  an  active  turning  to  the  right,  which  has  also  the  same 
sensation  as  its  result. 

8. 

At  the  time  when  my  work  on  the  Sensations  of  Move- 
ment was  written,  I  had  not  yet  attained  to  a  thoroughly 
comprehensive  view  of  the  simple  relation  here  described. 
I  encountered,  consequently,  difficulties  in  the  explanation 
of  certain  phenomena,  observed  partly  by  Breuer  and 
partly  by  myself,  which  are  now  easy  of  explanation,  and 

he  is  always  introducing  his  own  visual  presentations  by  way  of  inter- 
pretation. Even  so  acute  a  mind  as  Diderot's  can  fall  on  occasion 
into  the  strange  error  of  denying  that  the  blind  can  imagine  space. 
Cf.  Loeb's  work;  on  tactual  space  (p.  113,  above),  and  Heller's  Studien 
zur  Blindenpsychologie  (Leipzig,  1895).  See  Chapter  IX. 


138        THE  ANALYSIS  OF  SENSATIONS 

which  I  will  briefly  notice.  If  an  observer  be  shut  up  in 
a  closed  receptacle,  and  the  receptacle  be  set  in  rotation 
toward  the  right,  it  will  appear  to  the  observer  as  optically 
in  rotation,  although  every  ground  of  inference  for  relative 
rotation  is  wanting.  If  his  eyes  perform  involuntary  com- 
pensatory movements  to  the  left,  the  images  on  the  retina 
will  be  displaced,  with  the  result  that  he  has  the  sensation 
of  movement  toward  the  right.  If,  however,  he  fixes  his 
eyes  upon  the  receptacle,  he  must  voluntarily  compensate 
the  involuntary  movements,  and  thus  again  he  is  conscious 
of  movement  towards  the  right.  It  is  plain,  therefore,  that 
Breuer's  explanation  of  the  apparent  motion  of  optical 
vertigo  is  correct,  and  also  that  this  movement  cannot  be 
made  to  disappear  by  the  voluntary  fixation  of  the  eyes. 
The  remaining  cases  of  optical  vertigo  noticed  in  my  work 
may  be  disposed  of  in  like  manner.1 

In  voluntary  forward  motion  or  rotation,  we  have  not 
only  a  sensation  of  every  single  successive  position  of  the 
parts  of  our  body,  but  also  the  much  more  simple  sensation 
of  movement  forward  or  of  turning  round.  As  a  fact,  we 
do  not  compound  the  notion  of  forward  movement  from 
the  notions  of  the  various  individual  movements  of  the 
legs,  or  at  least  we  do  not  need  to  do  so.  There  are  cases, 
indeed,  in  which  the  sensation  of  forward  movement  is 
undoubtedly  present  while  that  of  the  movements  of  the 
legs  is  equally  undoubtedly  lacking.  This  is  true,  for 
instance,  of  a  railway  journey,  or  even  of  the  thought  of 
a  journey,  and  may  occur  also  in  recalling  a  distant  place, 
etc.  The  only  possible  explanation  of  this  can  be  that  the 

1  Grundlinien  der  Lehre  von  den  Bewegiingsempfindungen,  Leipzig, 
Engelmann,  1875,  p.  83. 


THE  ANALYSIS  OF  SENSATIONS        139 

will  to  move  forward  or  to  turn  about,  which  furnishes  to 
the  extremities  their  motor  impulses, — impulses  which  may 
be  further  modified  by  particular  innervations, — is  of  a  com- 
paratively simple  nature.  The  conditions  existing  here  are  pro- 
bably similar  to,  although  more  complicated  than,  those  con- 
nected with  the  movements  of  the  eyes,  which  Hering  has  so 
felicitously  interpreted,  and  to  which  we  shall  presently  return. 

We  shall  scarcely  go  far  wrong  if  we  suppose  that  the 
comparatively  simple  motor-sensations J  stimulated  from 
the  labyrinth  of  the  brain  stand  in  the  closest  connexion 
with  the  will  to  move.  These  motor-sensations  may  also 
correspond  to  the  feelings  of  direction  which  Riehl  has 
postulated  and  investigated,2  The  blind  man  has  them 
equally  with  the  man  of  normal  sight,  and  they  probably 
form  an  important  part  of  the  foundation  on  which  the 
understanding  of  tactual  space  reposes. 

I  summed  up  a  series  of  observations  on  optical  sensations 
and  motor-sensations  in  these  words  :  "  It  looks  as  if  visual 
space  would  turn  into  a  second  space,  which  is  held  to  be 
immovably  stationary,  although  this  second  space  is  char- 
acterized by  complete  absence  of  visibility."  The  space 
which  is  built  up  from  motor-sensations  seems,  in  fact,  to 
be  the  original  space.3 

At  that  time  I  was  preoccupied  with  physical  methods 
of  thought,  and  was  consequently  inclined  to  believe  that 
sensations  of  progressive  acceleration  behaved  in  a  manner 
completely  analogous  to  sensations  of  angular  acceleration. 
And  in  fact  every  physicist  who  studies  this  subject  is  liable 

1  Bewegungsempfindungen )  p.  124. 

2  Riehl,  Der philosophische  Kritizismus,  Vol.  II.,  p.  143. 

3  Beiuegtingsempfindtingen,  p.  26. 


140        THE  ANALYSIS  OF  SENSATIONS 

to  think  at  once  of  the  three  equations  for  the  rotatory 
movement  of  a  body  and  the  three  equations  for  its  move- 
ment of  translation.  I  believed  further,  that,  in  accordance 
with  the  principle  of  specific  energy,  we  ought  to  assume 
special  sensations  of  the  position  of  the  head. 

Breuer,1  in  a  later  piece  of  research,  has  made  it  probable 
that  the  sensations  of  progressive  acceleration  vanish  very 
much  more  quickly  than  those  of  angular  acceleration,  and 
that  perhaps  the  organ  of  the  former,  at  any  rate  in  human 
beings,  is  atrophied.  Further,  Breuer  finds  that,  except  for 
the  semicircular  canals,  B,  the  otolithic  apparatus,  <9,  with 
its  planes  of  sliding  corresponding  to  the  planes  of  the 
semicircular  canals,  is  the  only  organ  adapted  to  the  signaliz- 
ing of  progressive  accelerations  and  position  simultaneously. 
The  three  components  of  gravity  corresponding  to  the  three 
planes  of  sliding  characterize  the  position  of  the  head.  Every 
alteration  of  the  position  alters  these  components,  and  in- 
stantaneously sets  the  apparatus  of  the  semicircular  canals 
going.  But  progressive  accelerations  alter  these  components 
without  making  any  demands  on  the  semicircular  canals. 
Consequently,  according  to  Breuer,  the  three  combinations, 
O  alone,  O  +  B,  and  B  alone,  would  suffice  for  the  decision 
of  all  cases.  Thus  this  theory,  if  it  can  be  maintained, 
would  be  an  important  simplification. 

If  I  still  had  it  in  my  power  to  carry  out  experiments,  I 
would  submit  the  motor-sensations  in  themselves  to  a  re- 
newed and  thorough  investigation.  The  difference  in  the 
behaviour  of  the  sensations  of  angular  and  progressive 
accelerations  now  seems  to  me  significant.  Acceleration  of 

1  Breuer,  "  Ueber  die  Funktion  des  Otolithen-Apparates,"  Pfliiger's 
Archiv,  Vol.  XLVL,  p.  195. 


THE  ANALYSIS  OF  SENSATIONS        141 

rotation  gives  rise  to  a  sensation  which,  long  after  the 
acceleration  has  become  nil,  persists  with  a  decreasing 
force  which  can  be  quantitatively  x  measured.  Progressive 
acceleration  is  felt  in  its  pure  form  only  in  the  case  of 
vertically  accelerated  falling  or  rising.  When  the  accelera- 
tion vanishes  the  sensation  also  disappears  quickly.  The 
simplest  means  of  producing  a  constant  acceleration  in  a 
constant  direction  with  respect  to  the  body  is  by  uniform 
rotation.  We  soon  cease  to  have  any  sensation  of  uniform 
rotation.  But  a  constant  centrifugal  acceleration  also  does 
not  evoke  the  illusion  of  flying  away  in  its  direction,  but 
rather  calls  up  the  sensation  of  changed  position,  which 
sensation  again  vanishes  immediately  with  the  disappearance 
of  the  centrifugal  acceleration.  Does  this  mean  that  pro- 
gressive acceleration  exhausts  itself  as  a  stimulus,  or  that 
when  the  stimulus  becomes  constant  the  sensation  changes 
in  character  ?  In  that  case  we  shall  have  to  suppose  that 
the  sensation  is  composed  of  two  elements. 

We  have  sensations,  not  of  uniform  motion,  but  only  of 
acceleration.  To  the  elements  of  the  change  in  progressive 
and  angular  velocity  there  correspond  elements  of  the 
motor-sensations ;  and,  of  these,  those  sensations  at  any 
rate  which  correspond  to  angular  velocities  persist  with 
gradually  decreasing  force,  and  moreover  are  algebraically 
summable  just  like  the  sensations  corresponding  to  pro- 
gressive velocities ;  so  that  a  sensation  p,  corresponding 
to  the  total  change  in  velocity,  and  consequently  to  the 
velocity  attained  #,  is  correlated  with  a  movement,  usually 
of  velocity  nil  upwards,  set  up  in  a  short  time.2  Now  the 

1  Beweg^mgsem.pfind^^ngen,  p.  96,  Experiment  2. 
-  Bewegungsempfindungen,  pp.  116  sqq. 


142        THE  ANALYSIS  OF  SENSATIONS 

aggregate  of  sight  and-touch-impressions  that  we  passed  in 
review  increases  with  p  and  with  the  time  /.  We  need  not 
therefore  be  surprised  that  experience  teaches  us  to 
interpret  p  conceptually  as  a  velocity  and  pt  as  a  path, 
although  of  course  p  in  itself  has  nothing  to  do  with  con- 
cepts of  spatial  measurement.  In  this  way  it  seems  to 
me  that  we  get  rid  of  the  last  remaining  paradox  in  the 
theory  of  the  motor  sensations.  This  paradox  still  troubled 
me  in  1875,  and  I  see  that  it  has  also  troubled  others.1 


The  following  experiments  and  reflexions,  which  form  a 
sequel  to  an  earlier  publication  of  mine,2  will  perhaps  assist 
us  in  obtaining  a  correct  view  of  these  phenomena. 

If  we  take  our  stand  upon  a  bridge,  and  look  fixedly  at 
the  water  flowing  beneath,  we  shall  generally  have  the 
sensation  of  being  ourselves  at  rest,  whilst  the  water  will 
seem  in  motion.  Prolonged  gazing,  however,  as  is  well 
known,  almost  invariably  results  in  the  sensation  that 
suddenly  the  bridge,  with  the  observer  and  his  whole 
environment,  begins  to  move  in  the  direction  opposite  to 
that  of  the  water,  while  the  water  assumes  the  appearance 
of  being  at  rest.3  The  relative  motion  of  the  objects  is  in 

1  Bewegungsempfindungcn,  p.  122. 

8  Bewegungsempfindungen^  p.  85. 

3  As  we  all  know,  the  most  varied  forms  of  the  same  impression  are 
obtained  in  the  midst  of  a  number  of  railway  trains  some  of  which  are 
in  motion  and  some  at  rest.  A  short  time  ago,  while  making  a  steam- 
boat excursion  on  the  Elbe,  I  was  astonished  at  getting  the  impression, 
just  before  landing,  that  the  ship  was  standing  still  and  that  the  whole 
landscape  was  moving  towards  it — an  experience  that  will  be  readily 
understood  from  what  follows. 


THE  ANALYSIS  OF  SENSATIONS        143 

both  cases  the  same,  and  there  must  therefore  be  some 
adequate  physiological  reason  why  at  one  time  one,  and  at 
another  another,  part  of  them  is  felt  to  move.  In  order  to 
investigate  the  matter  at  my  leisure,  I  had  the  simple 
apparatus  constructed  which  is  represented  in  Fig.  18.  An 
oil-cloth  of  simple  pattern  is  drawn  horizontally  over  two 
rollers,  two  metres  long  and  fixed  three  metres  apart  in  bear- 
ings, and  is  kept  in  uniform  motion  by  means  of  a  crank. 
Across  the  oil-cloth  and  about 
thirty  centimetres  above  it, 
is  stretched  a  string  ff>  with 
a  knot  K,  which  serves  as  a 
fixation-point  for  the  eye  of 
the  observer  stationed  at  A. 
Now,  if  the  oil-cloth  be  set 
in  motion  in  the  direction  of 
the  arrow,  and  the  observer 

follow  the  pattern  with  his  eyes,  he  will  see  it  in  motion, 
himself  and  his  surroundings  at  rest.  On  the  other 
hand,  if  he  gazes  at  the  knot,  he  and  the  whole  room 
will  presently  appear  in  motion  in  the  contrary  direction 
to  the  arrow,  while  the  oil-cloth  will  stand  still.  This 
change  in  the  aspect  of  the  motion  takes  more  or 
less  time  according  to  the  mental  condition  of  the 
observer,  but  usually  requires  only  a  few  seconds.  If  we 
once  get  the  knack  of  it,  the  two  impressions  may  be  made 
to  alternate  with  some  rapidity  and  at  will.  Every  follow- 
ing of  the  oil-cloth  brings  the  observer  to  rest,  every  fixation 
of  K)  or  non-attention  to  the  oil-cloth,  by  which  its  pattern 
becomes  blurred,  sets  the  observer  in  motion.  Two  in- 
vestigators, for  whom  I  have  the  deepest  respect,  do  not 


144        THE  ANALYSIS  OF  SENSATIONS 

agree  with  me  as  to  the  result  of  this  experiment  in  the 
circumstances  indicated.  One  is  William  James,1  the  other 
Crum  Brown.2  I  have  performed  the  experiment  over  and 
over  again  with  the  same  result.  I  am  at  present  not  in 
a  position  to  carry  out  experiments,  and  must  consequently 
renounce  any  idea  of  a  new  test ;  but  the  method  of  after- 
images described  by  Brown  seems  to  have  much  to  recom- 
mend it.  I  pass  over  for  the  moment  the  different  possible 
theoretical  explanations  of  the  experiment. 


10. 

This  phenomenon,  of  course,  must  not  be  confounded 
with  the  familiar  Plateau-Oppel  phenomenon,  which  is  a 
local  retinal  effect.  In  the  preceding  experiment,  the  entire 
environment,  so  far  as  it  is  distinctly  visible,  is  in  motion, 
whilst  in  the  latter  a  moving  veil  is  drawn  along  in  front  of 
the  object,  which  is  at  rest.  The  attendant  stereoscopic 
phenomena, — for  example,  the  appearance  of  the  thread 
and  knot  underneath  the  transparent  oil-cloth, — are  quite 
immaterial  in  this  connexion. 

In  my  book  on  Bewegungsempfindungen  (p.  63)  I  made  it 
clear  that  the  Plateau-Oppel  phenomenon  was  the  result  ot 
a  peculiar  process,  which  had  nothing  to  do  with  the  other 
sensations  of  movement.  I  wrote  there  as  follows  : 

"  We  must  therefore  suppose  that,  during  the  movement 
of  an  image  on  the  retina,  a  peculiar  process  is  excited 
which  is  absent  during  rest,  and  that  in  the  case  of  move- 
ments in  opposite  directions,  very  similar  processes  are 

1  W.  James,  Principles  of  Psychology,  II.,  pp.  512,  sqq. 

2  Crum  Brown,  "  On  Normal  Nystagmus  "  (see  p.  133  above). 


THE  ANALYSIS  OF  SENSATIONS        145 

excited  in  similar  organs,  processes  which  are,  however, 
mutually  exclusive,  so  that  with  the  commencement  of  the 
one,  the  other  must  cease,  and  with  the  exhaustion  of  the 
one,  the  other  begins." 

This  statement  of  mine  seems  to  have  been  overlooked 
by  S.  Exner  and  Vierordt,  who  subsequently  expressed 
similar  views  on  the  same  subject. 


ii. 

Before  we  proceed  to  the  explanation  of  the  experiment 
(Fig.  1 8),  it  will  be  well  to  introduce  a  few  variations.  An 
observer  stationed  at  B  seems,  under  the  same  conditions, 
to  be  speeding,  with  all  his  surroundings,  towards  the  left. 
We  now  place  above  the  oil-cloth  T  T,  Fig.  1 9,  a  mirror 
S  S,  inclined  at  an  angle  of  45°  to  the  horizon.  We 
observe  the  reflexion  T  T'  in  S  S,  after  having  placed  on 
our  nose  a  shade  n  «,  which  intercepts 
the  direct  view  of  T  Thorn  the  eye,  O. 
If  TT  moves  in  the  direction  of  the 
arrow,  while  we  are  looking  at  Kf>  the 
reflexion  of  K^  we  shall  presently  fancy 
ourselves  sinking  downward  with  the 
whole  room,  whereas  if  the  motion  be 
reversed,  we  shall  seem  to  ascend  as  Fig- 19. 

if  in  a  balloon.1     Finally,  the  experi- 
ments with  the  paper  drum,  which  I  have  elsewhere  de- 


o 


1  Such  phenomena  often  make  their  appearance  quite  unsought.     As 
my  little  daughter  was  once  standing  near  a  window,  on  a  calm  winter's 
day,  during  a  heavy  snowfall,  she  suddenly  cried  out  that  she  and 
the  whole  house  were  rising  upward. 
K 


146        THE  ANALYSIS  OF  SENSATIONS 

scribed,1  and  to  which  the  following  explanation  also  applies, 
should  be  cited  here.  None  of  these  phenomena  are  purely 
optical,  but  all  are  accompanied  by  unmistakable  motor 
sensations  of  the  whole  body. 


12. 

What  form,  now,  must  our  thoughts  take  on,  in  order  to 
acquire  the  simplest  explanatory  setting  for  the  preceding 
phenomena  ?  Objects  in  motion  exert,  as  is  well  known,  a 
peculiar  motor  stimulus  upon  the  eye,  and  draw  our  atten- 
tion and  our  gaze  after  them.  If  the  eye  really  follows 
them,  we  must  assume,  from  what  has  gone  before,  that 
the  objects  appear  to  move.  But  if  the  eye  is  kept  for  some 
time  at  rest  in  spite  of  the  moving  objects,  the  constant 
motor  stimulus  proceeding  from  the  latter  must  be  com- 
pensated by  an  equally  constant  stream  of  innervation  flow- 
ing to  the  motor  apparatus  of  the  eye,  exactly  as  if  the 
motionless  point  on  which  the  eyes  rest  were  moving  uni- 
formly in  the  opposite  direction,  and  we  were  following  it 
with  our  eyes.  But  when  this  process  begins,  all  motion- 
less objects  on  which  the  eyes  are  fastened  must  appear  in 
motion.  It  is  obviously  unnecessary  that  this  stream  of 
innervation  should  always  be  consciously  and  deliberately 
called  into  action.  All  that  is  requisite  is  that  it  should 
proceed  from  the  same  centre  and  by  the  same  paths  as 
voluntary  fixation. 

No  special  apparatus  is  necessary  for  observing  the  fore- 

1  Bewegungsempfindtmgen,  p.  85.  For  more  recent  experiments  see 
A.  von,  Szily,  "  Bewegungsnachbild  und  Bewegungskontrast," 
Ztitschrift  far  Psychologic  nnd  Physiologic  der  Sinnesorgane,  1905. 
Vol.  XXXVIII.,  p.  81, 


THE  ANALYSIS  OF  SENSATIONS        147 

going  phenomena.  They  are  to  be  met  with  on  all  hands. 
I  walk  forward  by  a  simple  act  of  the  will.  My  legs  swing 
to  and  fro  without  my  having  to  attend  to  them  particularly. 
My  eyes  are  fixed  steadfastly  upon  my  goal  without  suffer- 
ing themselves  to  be  drawn  aside  by  the  motion  of  the 
retinal  images  consequent  upon  progression.  All  this  is 
brought  about  by  a  single  act  of  the  will,  and  this  act  of  the 
will  itself  is  the  sensation  of  forward  movement.  The  same 
process,  or  at  least  a  part  of  it,  must  also  be  set  up,  if  the 
eyes  are  to  resist  for  any  length  of  time  the  stimulus  of  a 
mass  of  moving  objects.  Hence  the  motor  sensations  ex- 
perienced in  the  above  experiments. 

The  eyes  of  a  child  in  a  railway  train  will  be  observed  to 
follow  almost  uninterruptedly  and  with  a  jerking  motion  the 
objects  outside,  which  appear  to  it  to  be  running.  The 
adult  has  the  same  sensation  if  he  will  passively  yield  him- 
self to  the  natural  impressions.  If  I  am  riding  forwards, 
the  whole  space  to  my  left,  for  obvious  reasons,  rotates,  in 
the  direction  of  the  hands  of  a  watch,  about  a  very  distant 
vertical  axis  and  the  space  to  my  right  does  the  same,  but 
in  the  opposite  direction.  Only  when  I  resist  following  the 
objects  with  my  eyes,  does  the  sensation  of  forward  motion 
arise. 


My  views  regarding  the  sensations  of  movement  have 
been  repeatedly  attacked,  as  is  well  known,  but  invariably 
the  adverse  arguments  have  been  aimed  solely  at  the 
hypothesis,  to  which  I  attached  comparatively  little  import- 
ance. That  I  am  ready  and  willing  to  modify  my  views  in 
accordance  with  newly  discovered  facts,  the  present  work 


148        THE  ANALYSIS  OF  SENSATIONS 

will  testify.     The  decision  as  to  how  far  I  am  in  the  right 
I  will  cheerfully  leave  to  the  future.     On  the  other  hand,  I 
should  like  to  mention  that  observations  have  been  made 
that  strongly  favor  the  theory  propounded  by  myself,  Breuer, 
and  Brown.     To  these  belong,  first,  the  facts  collected  by 
Dr.  Guye  of  Amsterdam  (Du    Vertigo  de  Meniere :  Rapport 
lu  dans  la  section  cFotologie  dit  congres  periodique  international 
de  sciences  medicales  a  Amsterdam^  1879).     Guye  observed, 
in  diseases  of  the  middle  ear,  that  reflex  turnings  of  the 
head  were  induced  when  air  was  blown  into  the  cavity  of 
the  tympanum,  and  found  a  patient  who  was  able  to  state 
exactly  the  direction  and  number  of  the  turnings  which  he 
had  felt  during  the  injection  of  liquids. — Prof.  Crum  Brown 
("On   a   Case   of   Dyspeptic  Vertigo,"  Proceedings  of  the 
Royal  Society  of  Edinburgh,   1881-1882),  has  described  an 
interesting  case  of  pathological  vertigo   observed  in  him- 
self, which  admitted  of  explanation,  as  a  whole,  by   the 
increased  intensity  and  lengthened  duration  of  the  sensa- 
tion incident  upon  every  turning  of  the  body. — But  most 
remarkable  of  all  are  the  observations  of  William  James 
("  The  Sense  of  Dizziness  in  Deaf-Mutes,"  American  Journal 
of  Otology,  Vol.   IV.,   1882).     James  discovered  in   deaf- 
mutes  a  striking  and  relatively  general  insensibility  to  the 
dizziness  of  whirling,  often  great  uncertainty  in  their  walk 
when  their  eyes  were  closed,  and  in  many  cases  an  astonish- 
ing loss  of  the  sense  of  direction  on  being  plunged  under 
water,  in  which  case  there  always  resulted  alarm  and  com- 
plete uncertainty  as  to  up  and  down.     These  facts  speak 
very  strongly  in  favor  of  the  view,  which  naturally  follows 
from   my   conception,   that    in    deaf-mutes   the    sense   of 
equilibrium  proper  is  considerably  degenerated,  and  that 


THE  ANALYSIS  OF  SENSATIONS        149 

the  two  other  senses  that  give  direction,  the  sense  of  sight 
and  the  muscular  sense  (the  latter  of  which  loses  all  its 
points  of  reference  when  the  weight  of  the  body  is  neutra- 
lized by  immersion  in  water),  are  rendered  proportionately 
more  necessary. 

It  is  impossible  to  maintain  the  view  that  we  arrive  at 
knowledge  of  equilibrium  and  of  movement  solely  by  means 
of  the  semi-circular  canals.  On  the  contrary,  it  is  extremely 
probable  that  lower  animals,  in  whom  this  organ  is  entirely 
wanting,  also  have  sensations  of  movement.  I  have  not  yet 
been  able  to  undertake  experiments  in  this  direction.  But 
the  experiments  which  Lubbock  has  described  in  his  work, 
Ants,  Bees,  and  Wasps,  become  much  more  comprehensible 
to  me  on  the  assumption  of  sensations  of  movement.  As 
experiments  of  this  sort  may  be  interesting  to  others,  it  will 
not  be  amiss  perhaps  to  consider  an  apparatus  which  I  have 
briefly  described  before  (Anzeiger  der  Wiener  Akademie, 
3oth  December  1876).  Other  apparatuses  of  the  same  kind 
have  since  been  constructed  by  Govi  and  Ewald.  They  have 
been  called  "cyclostats." 

The  apparatus  serves  for  the  observation  of  the  conduct 
of  animals  while  in  rapid  rotation.  Since,  however,  the 
view  of  the  animal  will  necessarily  be  effaced  by  the  rotatory 
motion,  the  passive  rotation  must  be  optically  nullified  and 
eliminated,  so  that  the  active  movements  of  the  animal 
alone  shall  be  left  and  rendered  observable.  The  optical 
neutralization  of  the  rotatory  motion  is  attained  simply  by 
causing  a  totally  reflecting  prism  to  revolve,  with  the  aid  of 
gearing,  above  the  disk  of  the  whirling  machine,  about 
exactly  the  same  axis,  in  the  same  direction,  and  with  half 
the  angular  velocity  of  the  disk. 


150        THE  ANALYSIS  OF  SENSATIONS 

Fig.  20  gives  a  view  of  the  apparatus.  On  the  disk  of  the 
whirling  machine  is  a  glass  receiver,  g,  in  which  the  animals 
to  be  observed  are  enclosed.  By  means  of  gearing  the  eye- 
piece o  is  made  to  revolve  with  half  the  angular  velocity 
and  in  the  same  direction  as  g.  The  following  figure  gives 
the  gearing  in  a  separate  diagram.  The  eyepiece  oo,  and 


Fig.  20. 

the  receiver  gg,  revolve  about  the  axis  A  A,  while  a  pair  of 
cog-wheels,  rigidly  connected  together,  revolve  about  BB. 
Let  the  radius  of  the  cog-wheel  act,  rigidly  connected  with 
gg,  be  =  r.  Then  r  is  the  radius  of  M,  and  2^/3  is  the 
radius  of  cct  but  the  radius  of  dd  is  =  4^/3,  wherewith 
the  desired  relation  of  velocity  between  oo  and  gg  is 
obtained. 

In  order  to  centre  the  apparatus,  a  mirror  S,  provided 
with  le veiling-screws,  is  laid  upon  the  bottom  of  the  receiver 


THE  ANALYSIS  OF  SENSATIONS        151 


and  so  adjusted  that,  on  rotation,  the  reflexions  in  it  remain 
at  rest.     It  is  then  perpendicular  to  the  axis  of  rotation.     A 
second  small  mirror,  *S',  in  the  silvering  of  which  is  a  small 
hole  Zj  is  so  adjusted  to  the  open  tube  of  the  eyepiece, 
with  its  reflecting  surface  downward,  that,  on  rotation,  the 
images  seen  through  the  hole,  in  the  mirrored  reflexion  of 
S'  in  S,  remain  motionless.     Then  S'  stands  perpendicular 
to  the  axis  of  the  eyepiece.     With  the  aid  of  a  brush  we 
may  now  mark  upon  the  mirror  S  a  point  P9  whose  position 
is  not  altered  on  rotation  (a  result  which  is  easily  accom- 
plished after  a  few  trials), 
and  so  place  the  hole  in 
the  mirror  S'  that  it  also 
remains    stationary     on 
rotation.      In   this   way     J 
points  on  both  axes  of 
rotation   are    found.     If 
now  —  by  means  of  screws 
—we  so  adjust  the  eye- 
piece,   that,   on   looking 
through  the  hole  in  S', 
the  point  P  on  S  and  the  reflexion  of  L  in  Sf  (or  really  the 
many  reflexions  of  P  and  Z)  fall  on  the  same  spot,  then 
the  two  axes  are  not  only  parallel  but  coincident. 

The  simplest  eyepiece  that  can  be  employed  is  a  mirror 
whose  plane  coincides  with  the  axis,  and  I  adopted  this 
device  in  the  initial  form  of  my  apparatus.  But  one-half  of 
the  field  of  vision  is  lost  by  this  method.  A  prism  of  total 
reflexion,  therefore,  is  much  more  advantageous.  Let  ABC 
(Fig.  22)  represent  a  plane  section  of  such  a  prismatic  eye- 
piece cut  perpendicularly  to  the  planes  of  the  hypothenuse 


Fig.  21. 


152        THE  ANALYSIS  OF  SENSATIONS 


and  the  two  sides.  Let  this  section  include,  also,  the  axis 
of  rotation  ONPQ,  which  is  parallel  to  AB.  The  ray 
which  passes  along  the  axis  QP  must,  after  refraction  and 
reflexion  in  the  prism,  proceed  again  along  the  axis  NO 
and  will  meet  the  eye  O  in  the  prolongation  of  the  axis. 
This  done,  the  points  of  the  axis  can  suffer  no  displacement 
from  rotation,  and  the  apparatus  is  centred.  The  ray  in 
question  must  accordingly  fall  at  M,  the  middle  point  of 
AB,  and,  hence,  since  it  falls  on  crown  glass  at  an  angle  of 
incidence  of  45°,  will  meet  AB 
at  about  16°  40'.  Therefore,  OP 
must  be  distant  about  0*115  AB 
from  the  axis, — a  relation  which 
can  best  be  obtained  by  trial,  by 
so  moving  the  prism  in  the  eye- 
piece that  oscillations  of  the 
objects  in  gg  during  rotation  are 
eliminated. 

Fig.  22  also  shows  the  field  of 
vision  for  the  eye  at  O.  The  ray 
OA,  which  falls  vertically  upon 
AC,  is  reflected  at  AB  in  the 
direction  AC  and  passes  out 
towards  S.  The  ray  OR,  on  the 
other  hand,  is  reflected  at  B  and  emerges,  after  refraction, 
in  the  direction  of  T. 

The  apparatus  has  hitherto  proved  quite  sufficient  for 
my  experiments.  If  a  printed  page  is  placed  in  gg,  and  the 
apparatus  turned  so  rapidly  that  the  image  on  the  retina  is 
entirely  obliterated,  one  can  easily  read  the  print  through 
the  eyepiece.  The  inversion  of  the  image  by  reflexion  could 


Fig.  22. 


THE  ANALYSIS  OF  SENSATIONS        153 

be  removed  by  placing  a  second,  stationary  reflecting  prism 
above  the  revolving  prism  of  the  eyepiece.  But  this  com- 
plication appeared  to  me  unnecessary. 

With  the  exception  of  a  few  physical  experiments,  I  have 
hitherto  undertaken  rotation-experiments  only  with  various 
small  vertebrates  (birds,  fishes),  and  have  found  the  data 
given  in  my  work  on  Motor  Sensations  fully  confirmed. 
However,  it  would  probably  be  of  advantage  to  make 
similar  experiments  with  insects  and  other  lower  animals, 
especially  with  marine  animals. 

Such  experiments  have  subsequently  been  carried  out, 
with  most  instructive  results,  by  Schafer  (Natunvissen- 
schaftliche  Wochenschrift,  No.  25,  1891),  by  Loeb  (Helio- 
tropismus  der  Tiere,  Wiirzburg,  1890,  p.  117),  and  by 
others.  In  my  lecture  "  On  Sensations  of  Direction " 
(Schriften  des  Vereins  zur  Verbreitung  naturwissenschaft- 
licher  Kenntnisse  in  Wien,  1897,  and  Populdrwissenschaft- 
liche  Vorlesungen,  3rd  edition,  1903)  will  be  found  the 
remainder  of  what  I  have  to  say  on  the  sense  of  direction. 
But  I  should  like  to  refer  particularly  to  Breuer's  researches 
on  the  otolithic  apparatus,  to  Pollak  and  Kreidl's  experi- 
ments on  deaf-mutes,  and  above  all  to  Ewald's  work  of 
fundamental  importance,  Ueber  das  Endorgan  des  Nervus 
octavus  (Wiesbaden,  1892).  In  the  third  volume  of  the 
Handbuch  der  Physiologic  des  Menschen  (1905),  by  W. 
Nagel,  there  is  a  full  account  of  the  "theory  of  the 
sensations  of  position,  movement,  and  resistance."  Since 
for  some  years  past  I  have  not  been  in  a  position  to 
follow  the  experimental  work  that  has  been  done  in  this 
department  with  any  closeness,  I  have  asked  Professor 
Josef  Pollak  to  give  an  account  here  of  so  much  of  the 


154        THE  ANALYSIS  OF  SENSATIONS 

most  recent  work  as  is  likely  to  interest  readers  of  this 
book.  Dr.  Pollak  has  very  kindly  complied  with  my 
request,  and  the  following  paragraphs  14-19  are  from 

his  pen. 

14. 

The  results  in  the  course  of  the  last  ten  years  of 
morphological  research  and  of  research  in  comparative 
and  experimental  physiology  in  connexion  with  the  laby- 
rinth of  the  ear  (the  cochlea,  the  semicircular  canals, 
and  the  otolithic  apparatus)  have  been  almost  without 
exception  favorable  to  the  Mach-Breuer  hypothesis. 

It  may  now  be  taken  as  proved  that  the  organ  of  hearing 
is  constituted  by  the  cochlea  alone,  and  that  the  vestibular 
apparatus  has  no  acoustic  functions.  A  complete  proof 
of  this  has  been  furnished  by  Biehl,1  who,  by  intracranial 
operations  on  sheep,  succeeded  in  severing  the  vestibular 
branch  of  the  acoustic  nerve  without  injuring  the  ramus 
cochlearis ;  the  result  was  that  disturbances  of  equilibrium 
were  produced,  though  the  sense  of  hearing  remained 
unaffected.  Further,  that  part  of  the  theory  of  the  static 
function  of  the  labyrinth  is  firmly  founded  and  scarcely 
open  to  attack,  which  regards  the  semicircular  canals  as 
sense-organs  that  serve  the  perception  of  turnings  of  the 
head  (and,  mediately,  of  the  body),  especially  since  this 
hypothesis  has  received  at  the  hands  of  Breuer  important 
modifications  based  on  his  anatomical  studies  of  the 
epithelial  hairs  of  the  ampullae.2 

1  Karl   Biehl,   "  Ueber    intrakranielle   Durchtrennung   des   Nervus 
vestibularis  und  deren  Folgen,"  Sitzungsberichte  of  the  Vienna  Academy 
of  Science,  1900. 

2  J.  Breuer,  "Studien  liber  den  Vestibularapparat,"  Ibid.,  Vol.  CXIL, 
1903. 


THE  ANALYSIS  OF  SENSATIONS        155 

This  hypothesis  now  runs  as  follows  :  — 

"  Persistent  uniform  rotations  are  not  felt,  however 
rapid  they  are  ;  but  the  beginning  and  end  of  the  rotation, 
acceleration  and  retardation,  are  felt.  The  ampullary 
apparatus  is  not  affected  by  angular  velocities  that  persist, 
but  only  by  positive  and  negative  angular  accelerations. 
These  cause  a  momentary  displacement  of  the  endolymph- 
ring  and  of  the  cupula  terminalis  (which  as  a  consistent 
mass  holds  the  epithelial  hairs  together  in  a  constant 
figure  of  fixed  shape),  and,  concomitantly,  set  up  a 
tension  of  the  cell-hairs  and  an  excitement  of  the  terminal 
apparatus  of  the  nerves  on  one  side  of  the  crista  involved. 
As  long  as  these  excitations  last,  they  give  rise  to  a  sensa- 
tion of  rotation,  which  persists  until  the  contrary  impulse 
of  negative  acceleration,  when  the  rotation  stops,  or  the 
gradual  effect  of  the  elasticity  of  the  stretched  complexes, 
restores  the  normal  state  of  things  again." 

The  system  of  semicircular  canals,  moreover,  possesses, 
like  all  other  sense-organs,  the  property  of  giving  rise  not 
only  to  sensations  but  also  to  reflexes  (Breuer,  Delage, 
Nagel).  Prominent  among  reactive  organs  are  the  muscles 
of  the  eyes,  which  communicate  rotations  to  the  eyes 
when  the  body  rotates. 


Previously,  however,  the  opinion  had  been  conjecturally 
put  forward  by  Mach  that  progressively  accelerated  motion 
could  exercise  no  influence  on  the  lymph  enclosed  in  the 
semicircular  canals;  he  had  also  suggested  that  special 
organs  exist  in  the  labyrinth  for  the  perception  of  accelera- 
tions and  for  the  sensation  of  the  position  of  the  head. 


156        THE  ANALYSIS  OF  SENSATIONS 

Breuer  then  succeeded  in  making  it  at  least  very  probable 
that  this  function  belongs  to  the  otolithic  apparatus.  He 
supposes  that  the  otoliths  exert,  by  means  of  their  weight, 
a  definite  pressure  on  the  hair-cells  underneath  them. 
Every  inclination  of  the  head  must  change  the  position 
of  the  sacculus,  and  consequently  that  of  the  sense- 
epithelia  also.  By  determining  the  position  of  the 
directions  in  which  the  otoliths  slide  for  different  positions 
of  the  head,  Breuer  shewed  that  an  unambiguous  pro- 
nouncement as  to  the  position  of  the  head  is  only  made 
possible  by  the  co-operation  of  the  two  sacks.  "  For  every 
position  of  the  head  there  is  only  one  definite  combina- 
tion of  magnitudes  of  gravitation  of  the  otoliths  in  the 
four  maculae.  When,  as  we  suppose,  the  gravitation  of  the 
otoliths  is  felt,  then  every  position  of  the  head  is  charac- 
terized by  a  definite  combination  of  these  sensations."  In 
the  case  of  acceleration  in  a  straight  line,  every  shock  that 
causes  motion  will  evoke,  owing  to  the  inertia  of  the 
otolithic  masses,  a  relative  acceleration  of  these  masses 
in  the  opposite  direction,  this  relative  acceleration  repre- 
senting the  adequate  sensational  stimulus. 

Heuristically,  this  part  of  the  hypothesis  is  now  on  a  very 
firm  footing.  It  has  become  the  basis  of  research  on 
the  lower  animals  in  which  otoliths  alone  occur,  and  in  the 
case  of  higher  animals  also  it  has  pointed  the  way  to  the 
isolation  and  experimental  testing  of  the  functions  of  the 
otoliths. 

From  the  mass  of  facts  concerning  the  lower  animals, 
which  have  been  discovered  of  recent  years,  I  will  only 
select  a  few  pregnant  instances.  The  phenomena  that 
result  on  the  removal  of  the  otoliths  have  been  studied, 


THE  ANALYSIS  OF  SENSATIONS        157 

also  the  behaviour  of  animals  under  rotation  and  the  com- 
pensatory movements.  The  experiments  of  Prentiss,1  are 
particularly  interesting.  He  first  repeated  Kreidl's  famous 
experiments  in  compelling  sloughing  Crustacea  to  absorb 
"  iron  "  otoliths  ;  he  confirmed  the  fact  that  the  behaviour 
of  these  towards  magnets  is  in  accordance  with  the  theory. 
But  he  was  also  so  fortunate  as  to  obtain  observations  on 
free-swimming  larvse  of  lobsters,  which  had  been  deprived 
of  the  power  of  growing  otoliths  after  they  had  sloughed 
their  skin.  He  was  able  to  convince  himself  that  they 
present  the  same  phenomena  as  full-grown  shrimps,  from 
which  the  otoliths  have  been  removed  :  they  roll  from  one 
side  to  another,  swim  with  belly  upwards,  are  more  easily 
turned  over  on  to  their  backs  than  normal  larvae,  and, 
when  they  are  blinded,  the  loss  of  equilibrium  is  still  more 
striking.  The  same  writer  also  describes  as  follows  the 
behaviour  of  a  crustacean  (Virbius  zostericula\  in  which 
the  statocyst  is  normally  absent. 

"  It  is  not  a  free-swimming  form,  but  attaches  itself  to 
grasses,  in  the  positions  that  are  independent  of  gravity. 
If  it  is  compelled  to  swim,  it  does  so  in  a  very  uncertain 
manner,  but  generally  back  upwards.  It  is  easily  turned 
over  on  to  its  back,  and,  once  in  this  position,  is  very  slow 
at  setting  itself  right.  Its  uncertain  manner  of  swimming 
is  reminiscent  of  that  of  other  Crustacea  after  their  stato- 
cysts  have  been  destroyed.  If  the  eyes  are  covered  with 
lamp-black,  all  sense  of  direction  in  swimming  is 
lost." 

The   experiments   of    Prentiss   recall    those    of   K.    L. 

1  "  The  Otocyst  of  Decapod  Crustacea,  its  Structure,  Development 
and  Functions,"  Bulletin  of  the  Museum  of  Comparative  Zoology ', 
Harvard,  1900-1.  (Quoted  by  Kreidl.) 


158        THE  ANALYSIS  OF  SENSATIONS 

Schafer.1  Schafer  rotated  the  larvae  of  frogs,  and  dis- 
covered that  the  first  appearance  of  rotatory  vertigo 
coincides  in  time  with  the  completion  of  the  formation  of 
the  semicircular  canals. 

Ach's  2  researches  on  frogs  are  important.  He  discovered 
that  the  otoliths  are  connected  with  the  lid-reflex  of  the 
crossed  side ;  from  the  fact  that,  in  the  case  of  a  frog  de- 
prived of  its  otoliths  and  subjected  to  rapid  movement, 
the  lid-reflex  vanishes  both  horizontally  and  vertically,  he 
concluded  that  the  function  of  the  otoliths  is  to  subserve 
displacements  of  the  body  in  a  straight  line  in  space. 


16. 

On  the  other  hand,  the  wheel-like  movements  of  the 
eyes  that  take  place  when  the  position  of  the  head  under- 
goes a  series  of  changes,  and  the  nystagmic  movements 
caused  by  rotation  and  by  passing  a  galvanic  current  through 
the  head,  have  long  been  known  and  have  been  sufficiently 
analysed.  The  typical  movements  of  the  head,  and  the 
jerking  movements  of  the  eyes  which  are  repeated  at 
regular  intervals  when  the  head  is  continuously  rotated 
or  when  a  galvanic  current  is  passed  through  it,  and  which 
can  also  be  easily  felt  through  the  closed  eyelids,  are  sure 
objective  signs  of  vertigo.  Nystagmus  of  eyes  and  head 
is  completely  absent  in  animals  without  a  labyrinth,  as  has 
been  shown  by  Ewald  in  the  case  of  doves,  and  by  Breuer 

1  K.  L.  Schafer,  "  Funktion  und  Funktionsentwicklung  der  Bogen- 
giinge,  Zeitschrift  fur  Psychologic  und  Physiologic  der  Sinnesorgane, 
1894. 

2  Ach,  "  Ueber  die  Otolithenfunktion  und  Labyrinth tonus,"  Pfliiger's 
Archiv,  Vol.  LXXXVL,  1900. 


THE  ANALYSIS  OF  SENSATIONS        159 

in  the  case  of  cats,  whose  nervous  octavus  had  been 
severed  on  both  sides.  Breuer  and  Kreidl  have  proved 
that  the  optical  distortion  of  the  vertical,  experienced  by 
anyone  who  rides  in  a  whirling  chair  or  sits  in  a  railway 
train  passing  quickly  enough  over  a  sharp  curve,  depends 
upon  a  real  wheel-like  movement  of  the  eyes.  Again,  we 
owe  to  Breuer  the  proof  that  individual  ampullae,  even 
when  isolated,  can  be  galvanically  stimulated ;  when  that 
is  done,  they  produce  a  movement  of  the  head  in  the 
plane  of  the  canal  involved,  whereas,  according  to  Breuer, 
the  consequence  of  diffused  stimulation  is  the  so-called 
galvanotropic  reaction,  consisting  in  an  inclination  of  the 
head  towards  the  anode. 

So  much  having  been  premised,  the  phenomena  observed 
by  James,1  Kreidl2  and  Pollak3  as  resulting  with  deaf- 
mutes  when  affected  with  rotatory  or  galvanic  vertigo,  can 
easily  be  explained  on  the  Mach-Breuer  theory.  Accord- 
ing to  Mygind,4  out  of  118  deaf-mutes  subjected  to  an 
anatomical  examination,  pathological  changes  of  the 
vestibulary  apparatus  were  present  in  56  per  cent. ;  50  to 
58  per  cent,  of  the  deaf-mutes  experimented  on  by  Kreidl 
felt  no  rotatory  vertigo ;  2 1  per  cent,  of  those  on  whom 
Kreidl  reproduced  the  conditions  of  Mach's  experiment 
with  the  whirling  chair,  did  not  succumb  to  the  illusion  as 
to  position  with  respect  to  the  vertical,  which  is  inevitable 

1  William  James,  American  Journal  of  Otology,  1887. 

2  A.    Kreidl,    "  Beitrage    zur   Physiologic   des    Ohrlabyrinths    auf 
Grund  von  Versuchen  bei  Taubstummen,"  Pfliiger's  Archiv,  Vol.  LI. 

3  J.  Pollak,  "  Ueber  den  galvanischen  Schwindelbei  Taubstummen," 
etc.,  7^^.,  Vol.  LIV. 

4  H.  Mygind,  "  Ueber  die  pathologisch-anatomischen  Veranderungen 
der  Gehororgane  Taubstummer,"  Ibid.,  Vol.  XXV. 


i6o         THE  ANALYSIS  OF  SENSATIONS 

in  normal  persons :  they  also  without  exception  displayed, 
when  rotated,  no  reflex  movements  of  the  eyes.  The 
explanation  of  the  lower  percentage  is  that,  according  to 
Mygind's  statistics,  the  semicircular  canals  are  more 
frequently  found  to  be  diseased  than  the  vestibule. 

Pollak  found  that  30%  of  the  deaf-mutes  he  investigated 
experienced  no  galvanic  vertigo,  and  that  most  of  the  deaf- 
mutes  who  display  no  eye-movements  and  no  illusion  as  to 
the  vertical  when  placed  on  the  rotating  platform  or  the 
whirling  chair,  are  also  devoid  of  the  characteristic  symptoms 
of  galvanic  vertigo.  Further  researches  by  Strehl,  Kreidl, 
Alexander  and  Hammerschlag  confirmed  these  facts  ;  the 
three  latter  discovered,  further,  that,  when  the  deaf-mutes 
were  divided  into  congenital  deaf-mutes  and  those  with 
acquired  deafness,  an  extremely  high  percentage  of  the 
former  (in  Kreidl  and  Alexander's  experiments  84°/0,  in 
Hammerschlag's  95%)  displayed  normal  galvanic  reaction, 
while  only  29%  of  the  subjects  with  acquired  deafness 
reacted  normally  to  the  galvanic  current. 

Congenital  deaf-mutes,  i.e.,  those  with  hereditary  degenera- 
tion, behave  in  this  connexion  in  the  same  way  as  Japanese 
dancing  mice,  the  explanation  of  whose  physiological 
behaviour  lies,  as  Kreidl  and  Alexander I  have  shewn,  in 
their  anatomical  structure. 

These  mice  are  completely  deaf,  and  progress  in  a  sprawl- 
ing, hobbling  fashion ;  to  a  superficial  observer  their  power 
of  equilibrium  seems  unimpaired ;  but  if  one  tries  experi- 
mentally to  get  them  to  move  along  a  narrow  path,  the 

1  Alexander  and  Kreidl,  "  Zur  Physiologic  des  Labyrinthes  der 
Tanzmaus,"  Pfliiger's  Archiv,  I.,  II.,  III.,  Vols.  LXXXIL, 
LXXXVIII. 


THE  ANALYSIS  OF  SENSATIONS        161 

high  degree  in  which  their  power  of  balance  is  defective 
becomes  immediately  obvious.  They  are  free  from  rotatory 
vertigo,  but  when  a  galvanic  current  is  passed  through  their 
heads  they  behave  like  normal  animals.  Anatomical 
examination  gives  the  following  results.  Destruction  of  the 
papilla  basilaris  cochleae,  advanced  emaciation  of  the  ramus 
inferior  of  the  eighth  nerve,  advanced  atrophy  of  the  spiral 
ganglion,  destruction  of  the  macula  sacculi,  medium 
emaciation  of  the  branches  and  roots  of  the  ramus  superior 
and  medius  of  the  eighth  nerve,  and  medium  diminution  of 
both  vestibular  ganglia. 


Among  recent  experiments  in  the  field  of  comparative 
physiology.  those  of  Dreyfuss1  seem  to  me  very  remarkable. 
He  observed  the  behaviour  of  normal  guinea-pigs,  and  of 
guinea-pigs  deprived  of  their  labyrinths  (operated  on  one 
side  only  and  on  both  sides),  when  placed  on  a  rotating 
platform,  his  special  object  being  to  study  the  compensatory 
movements  of  the  eyeball  and  the  head.  He  records  a 
striking  difference  in  the  behaviour  under  rotation  of  the 
operated  animal  as  contrasted  with  the  behaviour  of  the 
intact  animal.  The  animal  that  has  been  deprived  of  both 
labyrinths  remains  motionless  in  one  place  under  rotation  ; 
it  displays  no  displacement  of  the  longitudinal  axis  of  the 
vertebral  column,  and  no  nystagmus  of  head  or  eyes.  It 
is  unconscious  of  the  rotation.  To  prove  this,  Dreyfuss 
devised  the  following  experiment  in  feeding  the  guinea-pigs. 
If  four  of  them,  —  one  normal,  one  with  the  left,  one  with 

1  Dreyfuss,  "  Experimentale  Beitrage  zu  der  Lehre  von  der  nichtakus- 
tischen  Funktion  des  Ohrlabyrinthes,"  Pfluger's  Archiv,  Vol.  LXXXI. 


162         THE  ANALYSIS  OF  SENSATIONS 

the  right,  and  one  with  both  labyrinths  destroyed, — are 
placed  on  the  rotating  platform,  and  the  experimenter  waits 
until  they  have  all  begun  to  feed,  the  normal  guinea-pig 
stops  eating  during  rotation ;  the  guinea-pig  without  the 
right  labyrinth  goes  on  eating  while  the  rotation  is  to  the 
right,  and  stops  when  it  is  to  the  left;  the  one  without 
the  left  labyrinth  goes  on  eating  when  the  rotation  is  to  the 
left,  and  stops  when  it  is  to  the  right ;  and  the  one  with 
neither  labyrinth  goes  on  eating  whichever  the  direction  of 
rotation.  Breuer  and  Kreidl  obtained  analogous  results 
from  comparative  experiments  with  normal  and  acoustically 
defective  cats. 

1 8. 

Morphologically,  and  from  the  teleological  standpoint, 
Alexander's  work  on  the  organs  of  equilibrium  and  hearing 
in  animals  with  congenitally  defective  visual  apparatus,  the 
mole  (Talpa  europced}  and  the  blind  mouse  (Spalax  typhlus^ 
is  interesting.1 

It  is  well-known  that,  in  comparison  with  the  lower 
animals,  the  vestibular  apparatus  in  the  higher  animals  and 
in  man  is  defectively  developed.  In  the  case  of  all  animals 
that  are  able  to  move  in  air  or  water,  we  find  three  nerve- 
ends  carrying  statoliths ;  in  the  higher  mammals  there  are 
only  two.  As  regards  the  higher  animals,  Mach  and  Breuer 
have  repeatedly  emphasized  the  fact  "  that  they  are  far  from 
meaning  to  imply  that  the  labyrinth  alone  furnishes  the 
sensations  necessary  for  the  maintenance  of  equilibrium  ; 

1  G.  Alexander,  "  Zur  Frage  der  phylogenetischen  Ausbildung  der 
Sinnesorgane,"  Zeitschrift  fur  Psychologic  und  Physiologic  der  Sinnes- 
organe,  Vol.  XXXVIII. 


THE  ANALYSIS  OF  SENSATIONS        163 

rather  it  co-operates  to  this  end  with  the  sense  of  pressure 
and  the  muscular  sense,  as  well  as  with  the  sense  of  sight." 
It  has  never  been  denied,  and  is  indeed  quite  certain,  that 
absence  or  loss  of  the  labyrinth-sensations  can  to  a  large 
extent  be  replaced  by  the  other  sense-perceptions  just 
mentioned,  so  that,  as  Ewald  pre-eminently  has  shewn,  the 
major  functions  of  the  maintenance  of  equilibrium,  such  as 
walking  and  standing,  can  be  adequately  performed  even 
when  the  labyrinth-function  has  been  lost,  or  when  there  is 
some  congenital  defect  in  it.  We  see  this,  not  only  in  the_ 
case  of  operated  animals,  but  also  in  that  of  those  deaf 
mutes  in  whom  we  have  reason  to  assume  some  lesion  of 
the  semicircular  canals  (Breuer).  However,  James  and 
Krei'dl  have  shewn  that  deaf-mutes  who  are  not  subject  to 
rotatory  vertigo  are  very  unskilful  in  all  the  more  delicate 
problems  of  balance. 

The  mole,  on  the  other  hand,  is  an  animal  whose  move- 
ments take  place  principally  underground,  though  the 
surface  on  which  it  moves  is  solid  ;  moreover  it  dispenses 
almost  completely  with  any  sense  of  orientation  by  means 
of  the  organ  of  sight,  and  Alexander  has  shewn  that  this 
is  fully  compensated  by  its  exquisite  power  of  balance.  This 
is  anatomically  expressed  by  the  unusual  size  of  the  terminal 
nerve  cells,  by  the  relatively  large  number  of  the  sense-cells, 
and  especially  by  the  presence,  in  the  sinus  utricularis 
inferior,  of  a  macula  neglecta  which  is  wanting  in  other 
mammals,  and  which,  apart  from  birds  and  reptiles,  has 
only  been  found  in  one  other  lower  mammal,  Echidna 
aculeata. 

It  is  Alexander's  merit  to  have  proved  that,  in  respect 
of  the  structure  of  its  static  terminal  nerve-cells,  Echidna 


164        THE  ANALYSIS  OF  SENSATIONS 

represents  the  hitherto  unknown  transition  from  mammals 
to  birds.  Echidna  possesses  a  cortical  organ  which,  in  histo- 
logical  structure,  corresponds  with  that  of  mammals,  whereas 
in  the  number  of  the  other  terminal  points  of  nerves  it 
agrees  with  the  labyrinth  of  birds ;  in  addition  to  the  three 
macular  nerve-terminations  (macula  utriculi,  macula  sacculi, 
and  macula  lagenae)  it  exhibits  a  macula  neglecta  Retzii. 


19. 

The  results  of  these  researches,  of  which  only  a  small 
selection  has  been  mentioned,  may  be  summed  up  as  follows. 
The  compensation  in  the  visual  field  of  every  movement  of 
the  head  by  means  of  movements  of  the  eyes,  which  are 
carried  out  also  by  the  blind  and  by  normal  persons  with 
their  eyes  shut ;  the  absence  of  these  movements  in  many 
deaf-mutes ;  the  nystagmus  of  the  eyes  that  takes  place 
under  continued  rotation  ;  the  wheel-like  movement  of  the 
eyes  when  the  direction  of  the  acceleration  of  masses  in  the 
body  is  altered  by  a  centrifugal  force ;  rotatory  vertigo  and 
its  law;  the  absence  "of  this  vertigo  in  many  deaf-mutes; 
finally,  the  identical  character  of  galvanic  vertigo  in  man 
and  in  animals, — all  these  facts  serve  strongly  to  confirm 
the  theory  of  Mach  and  Breuer,  although  it  cannot  be  denied 
that  many  questions  still  remain  unsolved.  As  against  other 
hypotheses,  such  as  those  of  Ewald  and  Cyon,  this  theory  has 
at  any  rate  the  advantage  that,  in  the  case  of  the  ampullary 
and  otolithic  apparatus,  it  provides  a  clearer  explanation  of 
the  specific  disposition  to  the  adequate  stimulus  than  we 
have  for  any  other  sense  organ,  and  also  that,  in  accord- 
dance  with  it,  the  two  sense-organs  in  the  labyrinth  are 


THE  ANALYSIS  OF  SENSATIONS        165 

readily  brought  under  the  principle  of  specific  sense- 
energies  (Nagel).  In  any  case  the  sensation  of  motion  is 
proved  to  be  a  special  and  peculiar  department  of  sensa- 
tion. 

20. 

Professor  Pollak's  communication  here  comes  to  an  end. 

Without  doing  violence  to  the  facts  described  in  my 
book  on  The  Sensations  of  'Movement ',  the  preceding  observa- 
tions suggest  the  possibility  of  modifying  the  theoretical 
view  there  taken  of  the  facts,  as  we  shall  point  out  in  what 
follows.  It  remains  extremely  probable  that  an  organ 
exists  in  the  head — it  may  be  called  the  terminal  organ 
(TO] — which  reacts  upon  accelerations,  and  by  means 
of  which  we  are  made  aware  of  movements.  To  me  person- 
ally the  existence  of  sensations  of  movement,  of  the  same 
nature  as  other  sensations,  does  not  seem  doubtful,  and  I 
can  scarcely  understand  how  anyone,  who  has  really  re- 
peated on  himself  the  experiments  in  question,  can  deny 
the  existence  of  these  sensations. 

But  instead  of  imagining  that  the  terminal  organ  excites 
special  motor-sensations,  which  proceed  from  this  apparatus 
as  from  a  sense-organ,  we  might  also  assume  that  this  organ 
simply  disengages  innervations  after  the  manner  of  reflexes. 
Innervations  may  be  voluntary  and  conscious  or  involuntary 
and  unconscious.  The  two  different  organs  from  which 
these  proceed  may  be  designated  by  the  letters  WI  and 
UI.  Both  sorts  of  innervation  may  pass  to  the  oculo- motor 
apparatus  (OM)  and  to  the  locomotor  apparatus  (LM). 

Let  us  now  consider  the  accompanying  diagram.  We 
induce  by  the  will,  that  is  by  a  stimulus  from  WI>  an  active 


166        THE  ANALYSIS  OF  SENSATIONS 

movement,  which  passes  in  the  direction  of  the  unfeathered 
arrows,  to  OM  and  LM.  The  appropriate  innervation, 
whether  it  precedes  or  follows  the  movement,  is  directly 
felt.  In  this  case,  therefore,  a  specific  sensation  of  move- 
ment, differing  from  the  innervation,  is  unnecessary.  If  the 
motion  in  the  direction  of  the  unfeathered  arrows  is  a 
passive  one  (taking  us  by  surprise),  then,  as  experience 
shews,  reflexes  pass  from  TO  to  £77,  which  produce  com- 
pensatory movements,  indicated  by  the  feathered  arrows. 
If  WI  takes  no  part  in  the  process,  and  the  compensation 

is  effected,  both  the 
motion  and  the  neces- 
sity for  motor  sensa- 
tion are  absent.  But 
if  the  compensatory 
movement  is  inten- 
tionally suppressed, 
that  is,  by  intervention 
Fig.  23.  from  WI,  then  the 

same    innervation    is 

necessary  for  achieving  this  result  as  for  active  movement, 
and  it  consequently  produces  the  same  motor  sensation. 

The  terminal  organ  TO  is  accordingly  so  adjusted  to 
WI  and  UI  that  upon  a  given  motor  stimulus  in  the  first, 
contrary  innervations  are  set  up  in  the  last  two.  But 
further,  we  have  to  notice  the  following  difference  in  the 
relation  of  TO  to  fF/and  UI.  For  TO,  the  motor  excita- 
tion is  naturally  the  same  whether  the  movement  induced 
is  passive  or  active.  In  active  movements,  too,  the  inner- 
vations proceeding  from  WI  would  eventually  be  neutralized 
by  TO  and  UI,  did  not  an  inhibitory  innervation  proceed 


THE  ANALYSIS  OF  SENSATIONS        167 

simultaneously  with  the  willed  innervation  from  WI  to  TO 
or  UI.  The  influence  of  TO  upon  WI  must  be  conceived 
as  much  weaker  than  its  influence  upon  UI.  If  we  should 
picture  to  ourselves  three  animals,  WI,  UI,  and  TO, 
between  whom  there  was  a  division  of  labor,  such  that  the 
first  executed  only  movements  of  attack,  the  second  only 
those  of  defence  or  flight,  while  the  third  filled  the  post  of 
sentinel,  all  of  whom  were  united  into  a  single  new  organism 
in  which  WI  held  the  dominant  position,  we  should  have  a 
conception  approximately  corresponding  to  the  relation 
represented.  There  is  much  in  favor  of  such  a  conception 
of  the  higher  animals.1 

I  do  not  offer  the  preceding  view  as  a  complete  and 
perfectly  apposite  picture  of  the  facts.  On  the  contrary,  I 
am  fully  aware  of  the  defects  in  my  treatment.  But  the 
attempt  to  reduce  to  one  and  the  same  quality  of  sensation, 
in  accordance  with  the  cardinal  principle  evolved  in  our 
investigation  (p.  62),  all  sensations  of  space  and  movement 
which  arise  in  the  province  of  sight  and  touch  during 
change  of  place,  and  which,  even  when  locomotion  is  only 
remembered,  or  a  distant  spot  only  thought  of,  arise  in  a 
shadowy  form,  will  be  found  to  be  not  without  justification. 
The  assumption  that  this  quality  of  sensation  is  the  will, 
so  far  as  the  will  is  occupied  with  position  in  space  and 
spatial  movement,  or  that  it  is  innervation,  does  not  fore- 

1  If  I  grasp  a  little  bird  in  my  hand,  the  bird  will  behave  towards 
my  hand  exactly  as  a  human  being  would  towards  a  giant  cuttle-fish. — 
In  watching  a  company  of  little  children  whose  movements  are  largely 
unreflecting  and  unpractised,  the  hands  and  eyes  remind  one  very 
strongly  of  polypoid  creatures.  Of  course,  such  impressions  do  not 
afford  solutions  of  scientific  questions,  but  it  is  often  very  suggestive  to 
abandon  oneself  to  their  influence. 


168        THE  ANALYSIS  OF  SENSATIONS 

stall  future  investigation  and  only  represents  the  facts  as 
they  are  known  at  the  present  time.1 


21. 

From  the  discussions  of  the  previous  chapter  relative  to 
symmetry  and  similarity,  we  may  immediately  draw  the 
conclusion  that  to  like  directions  of  lines  which  are  seen, 
the  same  kind  of  innervation-sensations,  and  to  lines 
symmetrical  with  respect  to  the  median  plane  very  similar 
sensations  of  innervation  correspond,  but  that  with  looking 
upwards  and  looking  downwards,  or  with  looking  at  ob- 
jects afar  off  and  at  objects  near  at  hand,  very  different 
sensations  of  innervation  are  associated, — as  we  should 
naturally  be  led  to  expect  from  the  symmetrical  arrange- 
ment of  the  motor  apparatus  of  the  eye.  With  this  single 
observation  we  explain  at  once  a  long  chain  of  peculiar 
physiologico-optical  phenomena,  which  have  as  yet  received 
scarcely  any  attention.  I  now  come  to  the  point  which,  at 
least  from  the  physical  point  of  view,  is  the  most  important. 

The  space  of  the  geometrician  is  a  mental  construction 
of  three-dimensional  multiplicity,  that  has  grown  up  on  the 
basis  of  manual  and  intellectual  operations.  Optical  space 
(Hering's  "sight-space")  bears  a  somewhat  complicated 
geometrical  relationship  to  the  former.  The  matter  may 
be  best  expressed  in  familiar  terms  by  saying  that  optical 
space  represents  geometrical  space  (Euclid's  space)  in  a 

1  Compare  Hering's  opinion  given  in  Hermann's  Handbiich  der 
Physiologie^  Vol.  III.,  Part  I.,  p.  547.  I  do  not  wish  to  conceal  the 
method  by  which  I  was  led  to  my  theory,  although  now  the  view  repre- 
sented by  James,  Miinsterberg  and  Hering,  as  explained  in  Chapter 
VIII.,  seems  to  me  preferable. 


THE  ANALYSIS  OF  SENSATIONS        169 

sort  of  relievo-perspective — a  fact  which  can  be  teleo- 
logically  explained.  In  any  event,  optical  space  also  is  a 
three-dimensional  multiplicity.  The  space  of  the  geome- 
trician exhibits  at  every  point  and  in  all  directions  the 
same  properties — a  quality  which  is  by  no  means  charac- 
teristic of  physiological  space.  But  the  influence  of 
physiological  space  may  nevertheless  be  abundantly 
observed  in  geometry.  Such  is  the  case,  for  example, 
when  we  distinguish  between  convex  and  concave  curva- 
tures. The  geometrician  should  really  know  only  the 
amount  of  deviation  from  the  mean  of  the  ordinates. 


22. 

As  long  as  we  conceive  the  (12)  muscles  of  the  eye  to  be 
separately  innervated,  we  are  not  in  a  position  to  understand 
the  fundamental  fact  that  optical  space  is  presented  as  a 
three-dimensional  multiplicity.  I  felt  this  difficulty  for 
years,  and  also  recognized  the  direction  in  which,  on  the 
principle  of  the  parallelism  of  the  physical  and  the  psychical, 
the  explanation  was  to  be  sought ;  but  owing  to  my  defec- 
tive experience  in  this  province,  the  solution  itself  remained 
hidden  from  me.  All  the  better,  therefore,  am  I  able  to 
appreciate  the  service  rendered  by  Hering,  who  discovered 
it.  To  the  three  optical  space  co-ordinates,  viz.,  to  the 
sensations  of  height,  breadth  and  depth,  corresponds 
according  to  the  shewing  of  this  investigator  (Hering, 
Beitrdge  zur  Physiologic,  Leipzig,  Engelmann,  1861-1865; 
Die  Lehre  vom  binokularen  Sehen,  1868)  simply  a  threefold 
innervation,  which  turns  the  eyes  to  the  right  or  to  the 
left,  raises  or  lowers  them,  and  causes  them  to  converge, 


170        THE  ANALYSIS  OF  SENSATIONS 

according  to  the  respective  needs  of  the  case.  This  is  the 
point  which  I  regard  as  the  most  important  and  essential.1 
Whether  we  regard  the  innervation  itself  as  the  space- 
sensation,  or  whether  we  conceive  the  space-sensation  as 
before  or  behind  the  innervation,  —  a  question  neither 
easy  nor  necessary  to  decide,  —  nevertheless  Hering's 
account  throws  a  flood  of  light  on  the  psychical  obscurity 
of  the  visual  process.  The  phenomena  cited  by  myself 
with  regard  to  symmetry  and  similarity,  moreover,  accord 
excellently  with  this  conception.  But  it  is  unnecessary, 
I  think,  to  dwell  any  further  on  this.2 

1  This  is  the  point  to  which  reference  was  made  above  (p.  122,  note 
i,  p.  138). 

2  This  conception  also  removes  a  difficulty  which  I  still  felt  in  1871, 
and  to  which  I  gave  utterance  in  my  lecture  on  "  Symmetry  "  (Prague, 
Calve,   1872), — now  translated  into  English  in  my  Popular  Scientific 
Lectures,  Chicago,  1894, — in  the  following  words  :  "The  possession  of 
a  sense  for  symmetry  by  persons  who  are  one-eyed  from  birth  is  certainly 
an  enigma.     Yet  the  sense  for  symmetry,  although  originally  acquired 
by  the  eyes,  could  not  have  been  confined  exclusively  to  the  visual 
organs.     By  thousands  of  years  of  practice  it  must  also  have   been 
implanted  in  other  parts  of  the  human  organism,  and  cannot,  therefore, 
be  immediately  eliminated   on  the  loss  of  an  eye."     As  a  fact,  the 
symmetrical  apparatus  of  innervation  remains,    even    when   one   eye 
is  lost. 


VIII.  THE  WILL. 


i. 


IN  what  precedes,  the  phrase  "  the  will  "  has  often  been 
used,  and  has  always  been  intended  merely  to  denote  a 
generally  recognized  psychic  phenomenon.  I  do  not  mean 
by  the  will  any  special  psychical  or  metaphysical  agent,  nor 
do  I  assume  a  specific  psychical  causality.  Rather,  I  am 
convinced,  in  company  with  the  overwhelming  majority  of 
physiologists  and  modern  psychologists,  that  the  phenomena 
of  volition  must — to  put  it  briefly,  but  in  a  way  that 
everyone  can  understand — be  explained  by  means  of  the 
physical  forces  of  the  organism  alone.  I  would  not  lay  any 
special  emphasis  on  the  fact  that  this  is  a  matter  of  course, 
were  it  not  that  the  remarks  of  many  critics  have  shewn  the 
emphasis  to  be  necessary. 

The  movements  of  lower  animals,  and,  equally,  the  first 
movements  of  all  new-born  animals,  are  immediately  set 
free  by  some  stimulus;  they  follow  the  stimulus  quite 
mechanically;,  they  are  reflex  movements.  Nor  are  such 
reflex  movements  absent  in  the  later  stages  of  the  lives  of 
higher  animals,  and  when  the  occasion  arises  for  us  to 
observe  them  for  the  first  time  in  ourselves, — for  instance, 
the  sinew-reflexes, — we  are  as  much  surprised  by  them  as  by 
any  unexpected  event  in  our  environment.  The  behaviour 
of  the  young  sparrow  described  above  (p.  74)  depends  on 

reflex  movements.     The  chick  pecks  quite  mechanically  at 

171 


172        THE  ANALYSIS  OF  SENSATIONS 

everything  that  it  sees,  just  as  the  child  grasps  at  everything 
that  strikes  its  notice,  and,  on  the  other  hand,  withdraws 
its  limbs  from  every  unpleasant  contact  without  any  co- 
operation of  the  intellect.  For  there  are  fixed  organic 
arrangements  which  determine  the  preservation  of  the 
organism.  If  we  adopt  Hering's  views  on  living  sub- 
stance, according  to  which  living  substance  strives  towards 
the  equilibrium  of  the  antagonistic  processes  taking  place 
in  it,  we  shall  be  forced  to  ascribe  to  the  elements  of  the 
organism  themselves  this  tendency  towards  self-preservation 
or  actual  stability. 

Sensational  stimuli  can  be  partly  or  wholly  replaced  by 
memory-images.  All  memory-traces  that  remain  behind 
in  the  -  nervous  system  co-operate  with  the  sensations  to 
set  free,  to  assist,  to  inhibit  and  to  modify  the  reflexes.  It 
is  in  this  way  that  voluntary  movement  arises,  since  we  can 
conceive  voluntary  movement,  at  any  rate  in  principle,  as 
reflex  movement  modified  by  memories,  however  far  we 
may  fall  short  of  understanding  it  in  detail.  The  child  that 
has  once  burnt  itself  at  a  bright  flame  refrains  in  future  from 
grasping  at  the  flame,  because  the  grasp-reflex  is  inhibited 
by  the  antagonistic  avoidance-reflex  which  the  memory  of 
the  pain  sets  free.  The  chick  begins  by  pecking  at  every- 
thing; but  soon,  under  the  influence  partly  of  inhibitory 
and  partly  of  encouraging  memories  of  taste,  it  exercises  a 
choice.  The  gradual  transition  from  reflex  movement  to 
voluntary  action  can  be  very  prettily  followed  in  the 
case  of  our  sparrow  (p.  74  above).  For  the  reflecting 
subject,  the  characteristic  mark  of  voluntary  action,  as 
distinct  from  reflex  movement,  lies  in  the  subject's  re- 
cognition that  the  determining  factor  in  voluntary  action 


THE  ANALYSIS  OF  SENSATIONS        173 

is    his    own    presentations,    which   anticipate    this    action 
(p.   100  above). 

2. 

The  psychic  processes  that  accompany  voluntary  action 
and  voluntary  movement  have  been  admirably  analysed  by 
William  James x  and  by  Hugo  Miinsterberg.2  It  seems  a 
simple  and  natural  view  to  suppose  that  the  actual  move- 
ment is  associated  with  the  imagined  movement  in  the  same 
way  as  one  presentation  is  associated  with  another.  But 
as  regards  the  sensations  of  the  kind  and  amount  of  the 
movement,  and  of  the  amount  of  effort  involved,  which 
are  connected  with  the  execution  of  the  movement,  two 
opposite  views  are  taken.  According  to  one  view,  which 
is  held  by  Bain,  Wundt  and  Helmholtz,  the  innervation 
which  flows  to  the  muscles  is  itself  felt.  James  and 
Miinsterberg  take  a  different  view.  They  hold  that  all 
the  kinaesthetic  sensations  that  accompany  a  movement  are 
peripherally  excited  by  sensible  elements  in  the  skin,  the 
muscles  and  the  joints. 

Against  the  hypothesis  of  the  central  origin  of  the 
kinaesthetic  sensations  we  have  to  set,  first  and  foremost, 
the  observations  on  anaesthetic  subjects,3  who,  when  their 
sensations  are  cut  off,  are  able  to  give  no  account  of  the 
passive  movement  of  their  limbs,  although  they  are  able  to 
move  their  limbs  under  the  guidance  of  the  sense  of  sight. 
We  feel  the  exertion  of  a  faradised  muscle  just  as  much 
as  in  the  case  of  a  muscle  that  is  voluntarily  innervated.4 

1  W.  James,  Principles  of  Psychology ',  Vol.  II.,  pp.  486  sqq. 

2H.  Miinsterberg,  Die  Willenshandlung,  Freiburg  im  Breisgau,  1888. 

3  W.  James,  op.  fit.,  Vol.  II.,  p.  489. 

«  W.  James,  op.  at.,  Vol.  II.,  p.  502. 


174        THE  ANALYSIS  OF  SENSATIONS 

The  hypothesis  of  specific  sensations  of  innervation  is  not 
required  for  the  explanation  of  the  phenomena,  and,  on  the 
principle  of  economy,  is  consequently  to  be  avoided. 
Finally,  sensations  of  innervation  are  not  directly  observed. 
A  special  difficulty  is  constituted  by  certain  optical  pheno- 
mena, to  which  we  shall  return. 

The  law  of  association  connects  not  merely  processes 
that  emerge  into  consciousness  (presentations),  but  also  the 
most  diverse  organic  processes.  The  man  who  blushes 
readily  when  he  is  embarrassed,  whose  hands  sweat  readily, 
etc.,  generally  observes  these  processes  taking  place  in  him- 
self the  moment  he  is  reminded  of  them.  For  purposes  of 
study  Newton1  acquired  a  dazzling  after-image  by  gazing 
at  the  sun;  this  image  disappeared,  but  during  a  period  of 
several  months,  although  he  remained  for  several  days  in 
the  dark,  it  always  returned  with  full  sensational  intensity 
the  moment  he  reminded  himself  of  it.  It  was  only  by 
diverting  his  attention  by  a  long-continued  and  violent 
psychic  effort  that  he  was  able  to  get  rid  of  this  trouble- 
some phenomenon.  Boyle  narrates  a  similar  observation 
in  his  book  on  colors.  When  brought  into  connexion 
with  these  facts,  the  association  of  motor  processes  with 
presentations  ceases  to  appear  strange. 


An  apoplectic  stroke  which  I  experienced  in  1898,  with- 
out its  in  the  least  affecting  my  consciousness,  has  made 
me  personally  familiar  with  part  of  the  facts  now  under 

1  King's  Life  of  Locke,  1830,  Vol.  I.,  p.  404  ;  Brewster,  Memoirs  of 
Newton,  1855,  Vol.  I.,  p.  236. 


THE  ANALYSIS  OF  SENSATIONS        175 

consideration.  I  was  in  a  railway  train,  when  I  suddenly 
observed,  with  no  consciousness  of  anything  else  being 
wrong,  that  my  right  arm  and  leg  were  completely  paralysed; 
the  paralysis  was  intermittent,  so  that  from  time  to  time  I 
was  able  to  move  again  in  an  apparently  quite  normal  way. 
After  some  hours  it  became  continuous  and  permanent, 
and  there  also  set  in  an  affection  of  the  right  facial  muscle, 
which  prevented  me  from  speaking  except  in  a  low  tone 
and  with  some  difficulty,  I  can  only  describe  my  condition 
during  the  period  of  complete  paralysis  by  saying  that  when 
I  formed  the  intention  of  moving  my  limbs  I  felt  no  effort, 
but  that  it  was  absolutely  impossible  for  me  to  bring  my 
will  to  the  point  of  executing  the  movement.  On  the  other 
hand,  during  the  phases  of  imperfect  paralysis,  and  during 
the  period  of  convalescence,  my  arm  and  leg  seemed  to  me 
enormous  burdens  which  I  could  only  lift  with  the  greatest 
effort.  It  seems  to  me  plausible  to  suppose  that  this  was 
caused  by  the  energetic  innervation  of  other  muscle-groups 
in  addition  to  the  muscles  of  the  paralysed  extremities.1 
The  paralysed  limbs  retained  their  sensibility  completely, 
except  for  one  place  on  the  thigh,  and  thus  I  was  enabled 
to  be  aware  of  their  position  and  of  their  passive  movements. 
I  found  that  the  reflex  excitability  of  the  paralysed  limbs 
was  enormously  heightened;  this  expressed  itself  particu- 
larly in  violent  jerks  on  the  slightest  alarm.  Optical  and 
tactual  motor-images  persisted  in  my  memory.  Very  often 
during  the  day  I  formed  the  intention  to  do  something  with 
my  right  hand,  and  had  to  think  of  the  impossibility  of 
doing  it.  To  the  same  source  are  to  be  referred  the  vivid 
dreams  which  I  had  of  playing  the  piano  and  writing, 

1  W.  James,  op.  cit.y  Vol.  II.,  p.  503. 


176        THE  ANALYSIS  OF  SENSATIONS 

accompanied  by  astonishment  at  the  ease  with  which  I 
wrote  and  played,  and  followed  by  bitter  disappointment 
on  awaking.  Motor  hallucinations  also  occurred.  I  often 
thought  that  I  felt  my  paralysed  hand  opening  and  shutting, 
and  at  the  same  time  the  total  movement  seemed  to  be 
hampered  as  if  by  a  loose,  but  stiff  glove.  But  I  had  only 
to  look  to  convince  myself  that  there  was  not  the  slightest 
movement.  Over  the  flexors  of  this  hand  I  have  ac- 
quired a  very  slight  control,  but  over  the  extensors  none 
at  all. 

Since  the  sensibility  of  the  hand  is  preserved,  while  the 
power  of  voluntary  movement  is  lacking,  I  do  not  know 
how  to  explain  the  illusion  of  movement  properly,  even  on 
the  new  theory.  The  muscles  that  are  withdrawn  from  the 
influence  of  the  will  react  now  to  the  most  diverse  stimuli, 
so  that  the  hand  is  sometimes  extended  and  sometimes 
clenched.  Strong  tastes  of  different  qualities  seem  to  act 
as  stimuli  to  different  extents  on  different  muscles  of  my 
paralysed  hand.  Water  impregnated  with  sulphate  of 
magnesia,  for  example,  excites  involuntary  movements  of 
tension  in  the  thumb  and  the  two  fingers  next  to  it. 


The  theory  of  James  and  Miinsterberg  fits  these  facts, 
as  I  think,  without  any  straining,  and  we  ought  therefore  to 
consider  it  as  correct  in  essentials.  The  innervation  is  not 
felt,  but  the  consequences  of  the  innervation  set  up  new 
peripheral  sensible  stimuli,  which  are  connected  with  the 
execution  of  the  movement.  There  are,  however,  some 
difficulties  which  prevent  me  from  believing  that  this  view 


THE  ANALYSIS  OF  SENSATIONS        177 

which  was   originally  my   own,1   completely  explains   the 
facts. 

One  would  think  that  the  central  process  which  condi- 
tions the  mere  presentation  of  a  movement  must  differ  in 
some  respect  from  the  process  which  also  releases  an  actual 
movement.  To  be  sure,  the  strength  of  the  process,  the 
absence  of  antagonistic  processes,  and  the  extent  to  which 
the  innervation-centres  are  charged,  may  be  partial  deter- 
minants; but  still  it  is  scarcely  possible  to  deny  that 
further  explanation  is  required.  In  particular,  the  difference 
in  behaviour  of  the  muscles  of  the  eye  and  the  other 
muscles  that  can  be  excited  at  will  needs  closer  investiga- 
tion. Most  muscles  have  variable  amounts  of  work  to 
perform,  and  it  is  of  practical  importance  for  us  to  know 
these  amounts  approximately.  The  work  done  by  the  eye- 
muscles,  on  the  other  hand,  is  small,  and  is  always  exactly 
connected  with  the  alteration  in  position  of  the  eyes ;  this 
latter  alone  is  of  optical  importance,  while  the  work"  as  such 
is  matter  of  indifference.  This  may  be  the  reason  why  the 
kinaesthetic  sensations  play  such  a  much  greater  part  in  the 
case  of  the  muscles  of  the  extremities. 


5- 

Hering  2  has  shewn  how  small  is  the  importance  of  the 
sensations    proceeding    from    the    muscles    of    the  »-eye. 

1  Before  the  phenomena  connected  with  paralysis  of  the  eye-muscles 
were  known  to  me,  z'.<?.,  before  1863. 

2  Hering  in  Hermann's  Handbuch  der  Physiologie^  Vol.  III.,  I,  547. 
Cf.  also  Hillebrand,  "  Verhaltnis  der  Akkommodation  und  Konvergenz 
zur  Tiefenlokalisation,"  Zeitschrift  fur  Psychologic  und  Physiologic  der 
Sinnesorganet  Vol.  VII.,  pp.97,  sqq. 

M 


178        THE  ANALYSIS  OF  SENSATIONS 

Usually  we  scarcely  attend  at  all  to  the  movements 
of  our  eyes,  and  the  position  of  objects  in  space  remains 
uninfluenced  by  these  movements.  If  one  imagines  two 
spherical  surfaces,  covered  with  movable  retinae,  and 
remaining  fixed  in  space  while  the  retinse  revolve,  a  super- 
ficial consideration  might  even  induce  us  to  believe  that 
the  space-values  of  the  objects  seen  would  only  be  deter- 
mined by  the  two  positions  of  reflexion  on  the  fixed 
spheres.  But  the  facts  mentioned  on  p.  127  above,  compel 
us  to  separate  these  space-values  into  two  components,  one 
of  which  depends  on  the  co-ordinates  of  the  point  of 
reflexion  on  the  retina,  and  the  other  on  the  co-ordinates 
of  the  point  of  vision,  which  components  undergo  mutually 
compensating  alterations  corresponding  to  voluntary  altera- 
tions of  the  point  of  vision.1  Now,  if  we  refuse  to  admit 
a  sensation  of  innervation,  and  deny  the  importance  of 
the  peripherally  excited  kinaesthetic  sensations  of  the  eye- 
muscles,  the  only  remaining  alternative  is  that  adopted  by 
Hering, — namely  to  regard  the  position  of  attention  as 
determined  by  a  definite  psycho-physical  process,  which  at 
the  same  time  is  the  physical  factor  that  releases  the  corre- 
sponding innervation  of  the  eye-muscles.2  But  this  process 
is  still  a  central  process,  and  "attention  "  remains  scarcely 
different  from  "  the  will  to  see."  In  this  way  I  might  still 
hold  in  essentials  to  my  expression  on  p.  130  above;  for 
which  of  the  series  of  processes  excited  from  and  pro- 

1  Cf.  p.  114  above  ;  Hering,  op.  «?.,  pp.  533,  534.  I  am  now  unable 
to  decide  whether  the  view  that  the  alteration  of  the  space-values  is 
completed  immediately  with  the  change  in  attention  can  be  brought 
into  harmony  with  the  fact  mentioned  on  p.  130  above. 

-  Hering,    op.  cit.t  pp.  547,  548. 


THE  ANALYSIS  OF  SENSATIONS        179 

ceeding  from  the  centre  is  the  one  that  enters  into 
sensation,  is  a  many-sided  problem  which  can  for  the 
present  remain  unsolved. 


6. 

In  conformity  with  what  precedes,  we  might  replace,  in 
the  explanation  attempted  on  p.  166  above,  the  two 
antagonistic  innervations  by  two  antagonistic  processes  of 
attention,  one  excited  by  the  sensible  stimulus,  and  the 
other  a  central  process.  I  cannot  give  my  assent  to  the 
explanation  proposed  by  James1  of  the  phenomena  con- 
nected with  paralysis  of  the  muscles  of  the  eye,  since  this 
explanation  seems,  formally  at  any  rate,  to  drift  towards 
the  doubtful  waters  of  "  unconscious  inferences."  In  the 
case  under  discussion  we  are  concerned  with  sensations 
and  not  with  the  results  of  reflexions. 

The  function  of  the  muscles  of  the  eyes  is  merely  to 
ensure  our  orientation  in  space ;  that  of  the  muscles  of  the 
limbs  is  principally  the  performance  of  mechanical  work. 
We  thus  have  here  two  extreme  cases,  between  which  there 
will  lie  many  middle  terms.  When  we  see  the  newly- 
hatched  chick  pecking  and  hitting  its  mark  accurately,  it  is 
easy  to  believe  that  the  muscles  of  its  neck  and  head  to 
some  extent  perform  a  similar  office  to  that  of  its  eye- 
muscles,  and  act  as  an  apparatus  of  spatial  orientation. 
Probably  the  jerking  movements  of  the  head  which  take 
place  in  birds  when  they  walk  forward,  are  executed,  like 
nystagmic  movements  of  the  head  under  rotation,  in  the 

1  W.  James,  op.  cit.y  Vol.  II.,  p.  506. 


i8o        THE  ANALYSIS  OF  SENSATIONS 

interests  of  orientation.  The  muscles  of  the  extremities 
also  cannot  be  entirely  without  analogy  to  the  eye-muscles. 
Otherwise  how  could  we  understand  the  blind  man's  tactual 
presentation  of  space  ?  For  it  is  not  easy  to  combine  a 
nativistic  theory  of  visual  space  with  an  empirical  theory 
of  tactual  space.1 

1  Cf.  p.  135  above,  note  2,  and  p  138. 


IX.  BIOLOGICO-TELEOLOGICAL 
CONSIDERATIONS   AS   TO   SPACE.1 


i. 

WE  have  already  repeatedly  had  occasion  to  notice 
how  very  different  the  system  of  our  space-sensa- 
tions— our  physiological  space,  if  we  may  use  the  expression 
— is  from  geometrical  (by  which  is  here  meant  Euclidean) 
space.  This  is  true,  not  only  as  regards  visual  space,  but 
also  as  regards  the  blind  man's  tactual  space  in  comparison 
with  geometrical  space.  Geometrical  space  is  of  the  same 
nature  everywhere  and  in  all  directions,  it  is  unlimited  and 
(in  Riemann's  sense)  infinite.  Visual  space  is  bounded  and 
finite,  and,  what  is  more,  its  extension  is  different  in 
different  directions,  as  a  glance  at  the  flattened  "  vault  of 
heaven  "  teaches  us.  Bodies  shrink  when  they  are  removed 
to  a  distance  ;  when  they  are  brought  near  they  are  enlarged  : 
in  these  features  visual  space  resembles  many  constructions 

1  This  subject  cannot  be  treated  in  detail  here.  I  may  refer  to  my 
articles  in  The  Monist>  of  which  the  first  appeared  in  April  1901,  the 
second  in  July  1902,  and  the  third  in  October  1903.  The  physiological 
considerations  outlined  here  are  partly  related  to  Wlassak's  views  as 
stated  in  his  paper,  "  Ueber  die  statischen  Funktionen  des  Ohrlaby- 
rinthes "  Vierteljahrsschrift  fur  wissenschaftliche  Philosophic^  Vol. 
XVII.,  I,  p.  28),  except  that  I  assume,  not  one,  but  two,  reactions  to 
the  stimuli  in  question.  Cf.  also  the  passages  cited  above  from  Hering, 
and  W.  James,  Psychology,  Vol.  II.,  pp.  134,  sqq.  Cf.  also  my 
Erkenntnis  imd Itrtum,  1905,  pp.  331-414,  426-440, 

181 


182        THE  ANALYSIS  OF  SENSATIONS 

of  the  metageometricians  rather  than  Euclidean  space. 
The  difference  between  "above"  and  "below,"  between 
"  before  "  and  behind,"  and  also,  strictly  speaking,  between 
"right  and  left,"  is  common  to  tactual  space  and  visual 
space.  In  geometrical  space  there  are  no  such  differences. 
For  man,  and  for  animals  of  similar  structure  to  man, 
physiological  space  is  related  to  geometrical  very  much  as 
a  "triclinal"  is  to  a  "tesseral"  medium.  This  is  true  for 
men  and  animals,  so  long  as  they  are  not  endowed  with 
freedom  of  movement  and  of  orientation.  When  mobility 
is  added,  physiological  space  approximates  to  Euclidean, 
though  without  completely  attaining  to  the  simplicity  of  the 
properties  of  Euclidean  space.  Three-dimensional  multi- 
plicity and  continuity  are  common  to  geometrical  and  to 
physiological  space.  To  the  continuous  movement  of  a 
point  A  in  geometrical  space,  corresponds  a  continuous 
movement  of  a  point  A'  in  physiological  space.  We  have 
only  to  remember  the  difficulties  which  the  doctrine  of  the 
antipodes  had  to  overcome,  to  see  how  geometrical  space- 
presentations  can  be  disturbed  by  physiological.  Even  our 
most  abstract  geometry  does  not  employ  purely  metrical 
notions,  but  uses  also  such  physiological  conceptions  as 
direction,  sense,  right,  left,  etc. 

In  order  to  keep  the  physiological  and  geometrical 
factors  completely  apart,  we  have  to  reflect  that  our  space- 
sensations  are  determined  by  the  dependence  of  the 
elements  which  we  have  called  ABC...  upon  the 
elements  of  our  body  K  L  M  .  .  .  but  that  geometrical 
conceptions  are  formed  by  means  of  the  spatial  comparison 
of  bodies — by  the  relations  of  the  A  B  C's  ...  to  one 
another. 


THE  ANALYSIS  OF  SENSATIONS        183 


If  we  consider  the  spatial  sensations  not  as  isolated 
phenomena,  but  in  their  biological  connexion,  in  their 
biological  function,  they  become  easier  to  understand,  at 
any  rate  teleologically.  As  soon  as  an  organ  or  a  system  of 
organs  is  stimulated,  movements  take  place  as  reflex 
reactions ;  these  movements  are  generally  purposive,  and 
may  be  defensive  or  offensive,  according  to  the  nature 
of  the  stimulus.  For  example,  different  places  on  the  skin 
of  a  frog  may  be  successively  stimulated  by  dropping  acid 
on  them.  To  each  excitation  the  frog  will  reply  by  a 
specific  defensive  movement  according  to  the  spot  stimu- 
lated. The  stimulation  of  places  on  the  retinae  sets  free 
the  equally  specific  reflex  of  snapping.  That  is  to  say, 
alterations  that  make  their  entrance  into  the  organism  by 
different  paths  are  reproduced  externally  also  by  different 
paths  on  the  animal's  environment.  Now,  let  us  suppose 
that,  in  complicated  conditions  of  life,  such  reactions  can 
also  arise  spontaneously  by  memory,  that  is  to  say,  on  a 
slight  impulse,  and  that  they  can  be  modified  by  memories ; 
then  traces,  corresponding  to  the  nature  of  the  stimulus 
and  to  the  stimulated  organs,  must  remain  behind  in  the 
memory.  As  our  observation  of  ourselves  teaches  us,  we  not 
only  recognize  identity  of  quality  in  the  stimulus  of  burning, 
whatever  be  the  spot  burnt,  but  at  the  same  time  we 
distinguish  between  the  spots  stimulated.  We  must  there- 
fore suppose  that  there  is  attached  to  the  qualitatively 
identical  sensation  an  element  of  difference,  which  depends 
on  the  specific  nature  of  the  elementary  organ  stimulated, 
on  the  spot  stimulated,  or,  to  use  Hering's  expression,  on 


184        THE  ANALYSIS  OF  SENSATIONS 

the  "place  of  attention."  It  is  precisely  in  the  perception 
of  space  that  the  intimate  mutual  biological  adaptation  of  a 
multiplicity  of  connected  elementary  organs  is  displayed 
with  peculiar  clearness. 

3- 

Let  us  assume  only  one  kind  of  element  of  consciousness, 
namely  sensations.  In  so  far  as  we  have  spatial  perceptions, 
these  depend,  according  to  our  theory,  on  sensations.  What 
is  the  nature  of  these  sensations,  and  what  organs  are  active 
in  connexion  with  them,  we  must  leave  an  open  question. 
We  have  to  imagine  a  system  of  elementary  organs  of 
common  embryological  origin  as  being  naturally  so  arranged 
that  neighbouring  elements  display  the  greatest  ontological 
affinity,  and  that  this  affinity  decreases  as  the  segregation 
of  the  elements  from  one  another  increases.  The  organic 
sensation,  which  alone  depends  upon  the  individuality  of 
the  organ,  and  which  varies  with  the  variation  in  the  degree 
of  affinity,  will  correspond  to  the  sensation  of  space,  and 
from  this  we  distinguish  the  sensations  which  depend  on 
the  quality  of  the  stimulus  as  specific  sensations.  Organic 
sensations  and  specific  sensations  can  only  appear  con- 
comitantly.1  But,  over  against  the  varying  specific  sensa- 
tions, the  unchanging  organic  sensations  presently  constitute 
a  fixed  register,  in  which  the  former  are  arranged.  We  are 
here  only  making  as  to  the  elementary  organs  similar  pre- 
suppositions such  as  we  should  find  natural  in  the  case  of 
separated  individuals  of  the  same  descent  but  of  different 
degrees  of  affinity. 

1  Similarly  the  internal  organs  are  only  sensed  and  localized  when 
some  disturbance  of  their  equilibrium  takes  place. 


THE  ANALYSIS  OF  SENSATIONS        185 


The  perception  of  space  has  arisen  from  biological 
necessities,  and  can  best  be  understood  by  reference  to 
these  necessities.  An  endless  system  of  space-sensations 
would  not  only  be  purposeless  for  the  organism,  but  would 
also  be  physically  and  physiologically  impossible.  Space- 
sensations  which  should  be  orientated  with  reference  to 
the  body  would  also  be  valueless.  It  is  also  advantageous 
that,  in  visual  space,  the  sensation-indices  for  nearer  objects, 
which  are  biologically  the  most  important,  should  be  more 
sharply  graded,  while  as  regards  more  remote,  and  con- 
sequently less  important,  objects,  the  limited  supply  of 
indices  is  used  economically.  This  relation,  again,  is  the 
only  one  physically  possible. 

The  following  considerations  enable  us  to  understand  the 
motor  organization  of  the  visual  apparatus.  The  greater 
clearness  and  the  finer  distinctions  that  exist  at  a  given 
spot  on  the  retina  of  the  eye  of  a  vertebrate  are  an  economic 
arrangement.  By  this  means  a  movement  of  the  eyes  that 
follows  a  change  of  attention  is  recognized  as  advantageous, 
just  as  the  influence  of  a  voluntary  movement  of  the  eyes 
on  the  space-sensation  caused  by  objects  at  rest  is  re- 
cognized as  disadvantageous,  if  it  is  misleading.  Neverthe- 
less the  displacement  of  images  on  the  retina,  which  itself 
remains  at  rest,  is  biologically  necessary,  in  order  to  enable 
us  to  perceive  moving  objects  with  our  eyes  at  rest :  the 
only  case  in  which  it  is  unnecessary  for  the  organism,  is 
the  very  rare  one  when  it  is  required  to  perceive  an  object 
at  rest  when  the  eye  is  moved  by  some  cause  that  does  not 
emerge  into  consciousness,  such  as  an  external  mechanical 


186        THE  ANALYSIS  OF  SENSATIONS 

force  or  a  twitching  of  the  muscles.  The  only  solution  that 
provides  for  all  the  foregoing  requirements  is  that,  when  the 
eye  is  moved  voluntarily,  the  displacement  of  images  on  the 
retina  corresponding  to  this  movement  should  be  com- 
pensated by  the  voluntary  movement  in  respect  of  space- 
value.  But  from  this  it  follows,  that  when  the  eye  is  kept 
still,  the  mere  intention  to  move  the  eye  must  cause  objects 
at  rest  to  undergo  some  displacement  in  visual  space.  By 
means  of  a  suitable  experiment  (p.  128  above)  the  existence 
of  the  second  also  of  the  two  mutually  compensatory  com- 
ponents is  directly  proved.  These  organic  arrangements 
are  ultimately  the  reason  why  under  peculiar  circumstance, 
when  our  eyes  are  at  rest,  objects  at  rest  appear  to  move 
and  the  space-values  to  fluctuate, — why  we  see  bodies  in 
motion,  which  nevertheless  do  not  change  their  position 
relative  to  our  body,  and  neither  move  farther  away  nor 
come  nearer.  What  seems  paradoxical  under  these  peculiar 
circumstances,  is,  under  ordinary  circumstances  (those  of  spon- 
taneous locomotion)  of  the  highest  biological  importance. 

The  relations  of  tactual  space  are,  apart  from  certain 
peculiarities,  similar  to  those  of  visual  space.  The  sense 
of  touch  is  not  a  long-range  sense ;  there  is  no  perspec- 
tival  shrinkage  and  enlargement  of  tactual  objects.  But 
otherwise  the  phenomena  which  we  find  here  are  akin 
to  those  of  vision.  The  finger-tips  correspond  to  the 
macula  lutea.  We  can  tell  the  difference  perfectly  well 
between  passing  our  finger-tips  over  a  motionless  object 
and  the  movement  of  an  object  over  our  motionless  finger- 
tips. Analogous  paradoxical  phenomena  connected  with 
rotatory  vertigo  appear  here  also.  They  were  known  to 
Purkinje. 


THE  ANALYSIS  OF  SENSATIONS        187 


Biological  considerations  of  a  general  nature  force  us  to 
conceive  optical  and  tactual  space  as  homogeneous.  A 
newly-hatched  chick  notices  a  small  object  and  at  once 
both  looks  and  pecks  at  it.  The  stimulus  excites  a  certain 
tract  of  the  sense-organ  and  of  the  central  organ,  by  means 
of  which  both  the  looking  movement  of  the  eye-muscles  and 
the  pecking  movement  of  the  muscles  of  the  head  and  neck 
are  released  perfectly  automatically.  The  excitement  of  one 
and  the  same  nerve-tract,  which,  on  the  one  hand,  is  deter- 
mined by  the  geometrical  position  of  the  physical  stimulus, 
must,  on  the  other  hand,  be  regarded  as  the  foundation  of 
the  sensation  of  space.  A  child  that  notices  a  glittering 
object,  then  looks  at  it  and  grasps  at  it,  behaves  in  the 
same  way  as  the  chick.  In  addition  to  optical  stimuli  there 
are  others — acoustic  stimuli,  stimuli  of  heat  and  smell — 
which  can  also  release  movements  of  grasping  or  of  defence ; 
and  these  of  course  are  operative  with  blind  people  also. 
Again,  the  same  places  of  stimulus  and  the  same  sensations 
of  space  will  correspond  to  the  same  movements.  In 
general,  the  stimuli  that  excite  a  blind  person  are  only  con- 
fined to  a  narrower  sphere  and  are  less  clearly  and  definitely 
localized.  The  system  of  his  space-sensations  will  con- 
sequently be  rather  poorer  and  more  blurred  than  that  of 
a  normal  person,  and,  in  the  absence  of  a  special  education, 
will  even  remain  so.  Consider,  for  example,  a  blind  man 
who  tries  to  keep  off  a  wasp  that  is  buzzing  round  him. 

Accordingly  as  an  object  stimulates  me  to  turn  my  gaze 
upon  it,  or  stimulates  me  to  seize  it,  the  tracts  of  the  central 
organ  that  come  into  play  must  be  partially  different, 


i88        THE  ANALYSIS  OF  SENSATIONS 

although  adjacent.  If  the  two  stimuli  take  place  at  once, 
the  tract  involved  is  of  course  larger.  On  biological 
grounds  we  should  expect  that  the  space-sensations  con- 
nected with  different  senses,  which,  though  not  identical, 
are  closely  akin  to  one  another,  would  be  linked  together 
by  means  of  the  movements  which  they  induce, — move- 
ments which  are  directed  to  the  preservation  of  the 
organism, — would  merge  into  one  another  by  way  of 
association,  and  would  mutually  support  one  another ;  and 
this  is  in  fact  the  case. 

But  this  conclusion  does  not  exhaust  the  phenomena 
with  which  we  are  concerned.  A  chick  may  look  at  an 
object  or  may  peck  at  it ;  it  may  also  be  determined  by 
the  stimulus  to  turn  towards  it  and  to  run  up  to  it. 
Exactly  similar  is  the  behaviour  of  a  child  that  crawls 
towards  some  goal,  and  then  one  day  stands  up  and  runs  a  few 
steps  towards  the  goal.  All  these  cases  pass  gradually  over 
into  one  another,  and  we  have  to  think  of  them  all  as  homo- 
geneous. Probably  there  are  always  certain  parts  of  the  brain 
which!  when  stimulated  in  a  relatively  simple  manner,  deter- 
mine space-sensations  on  the  one  hand,  and  on  the  other  hand 
release  automatic  movements  which  are  sometimes  extremely 
complicated.  Optical,  thermal,  acoustic,  chemical  and 
galvanic  stimuli  can  excite  a  great  deal  of  locomotion  and 
change  of  orientation,  and  these  effects  can  be  produced  even 
in  animals  that  are  blind,  either  originally  or  by  degeneration. 


6. 

When  we  observe  a  millipede  (fulus)  crawling  regularly 
on  its  way,  we  cannot  resist  the  thought  that  a  uniform 


THE  ANALYSIS  OF  SENSATIONS        189 

current  of  stimulus  proceeds  from  some  one  of  the  insect's 
organs,  and  that  the  motor  organs  of  the  successive 
segments  of  the  body  reply  to  this  current  with  rhythmic 
automatic  movements.  The  longitudinal  wave,  which 
seems  to  pass  along  the  insect's  rows  of  feet  with  machine- 
like  regularity,  arises  from  the  difference  in  phase  of  the 
segments  behind  as  compared  with  those  in  front.  We 
should  expect  to  find  analogous  processes  in  the  more 
highly  organized  animals,  and  in  fact  such  processes  occur. 
I  need  only  refer  to  the  phenomena  connected  with  stimula- 
tions of  the  labyrinth,  for  instance  to  the  well-known 
nystagmic  movements  of  the  eyes,  which  are  released  under 
active  and  passive  rotation.  Now,  if  there  are  organs,  as  in 
the  case  of  the  millipede,  by  the  simple  stimulation  of 
which,  the  complicated  movements  of  a  definite  kind  of 
locomotion  are  induced,  then  we  may  regard  this  simple  stimu- 
lation, in  the  case  where  it  is  present  to  consciousness,  as  the 
will  to  the  locomotion  in  question,  or  as  the  attention  to 
the  locomotion,  which  automatically  draws  the  locomotion 
after  it.  At  the  same  time,  we  recognize  that  it  is  a  necessity 
for  the  organism  to  feel  the  effect  of  the  locomotion  in  a 
correspondingly  simple  manner.  And,  in  fact,  objects  of 
sight  and  touch  do  appear  with  varying  and  fluctuating 
space-values,  instead  of  their  values  being  stable.  Even  if 
we  exclude  all  sensations  of  sight  and  touch  as  completely 
as  possible,  there  still  remain  sensations  of  acceleration, 
which  evoke,  by  way  of  association,  the  images  of  the 
various  space-values  with  which  they  have  often  been  con- 
nected. Between  the  first  and  last  members  of  the  process 
lie  the  sensations  of  movement  in  the  extremities,  whicrij 
however,  are  usually  only  fully  present  to  consciousness 


igo        THE  ANALYSIS  OF  SENSATIONS 

when  some  obstacle  arises  and  makes  a  modification  of  the 
movement  necessary. 

The  man  who  is  motionless  as  a  whole  is  only  aware  of 
space-sensations  which  are  limited,  locally  individualized, 
and  orientated  with  reference  to  his  own  body;  but  the 
sensations  which  arise  on  occasion  of  locomotion  and 
change  of  orientation  possess  the  character  of  regularity 
and  inexhaustibility.  All  these  experiences  are  required 
as  a  basis  for  the  construction  of  a  conception  of  space 
approximately  similar  to  Euclidean  space.  Apart  from  the 
fact  that  the  first  set  of  experiences  only  gives  us  agree- 
ments and  differences,  but  no  magnitudes  and  no  metrical 
determinations,  the  latter  set  does  not  attain  absolute 
uniformity  on  account  of  the  obstacles  in  the  way  of 
permanent  and  free  disorientation  in  respect  of  the 
vertical. 


For  the  animal  organism,  the  relations  between  the  parts 
of  its  own  body  are,  first  of  all,  of  the  highest  importance. 
An  alien  object  only  acquires  value  by  standing  in  relation 
to  parts  of  the  animal's  own  body.  In  the  lowest  organisms 
the  sensations,  including  the  space-sensations,  are  sufficient 
to  secure  adaptation  to  primitive  conditions  of  life,  But 
as  these  conditions  become  more  complicated  they  force 
on  the  development  of  the  intellect.  Then  the  mutual 
relations  of  those  functional  complexes  of  elements 
(sensations)  which  we  call  bodies,  acquire  an  indirect 
interest.  Geometry  arises  from  the  spatial  comparison 
of  bodies  with  one  another. 

Our  understanding  of  the  development  of  geometry  may 


THE  ANALYSIS  OF  SENSATIONS        191 

be  assisted  by  the  observation  that  our  immediate  interest 
is  connected,  not  with  spatial  properties  alone,  but  with 
the  whole  permanent  complex  of  material  properties  which 
is  important  for  the  satisfaction  of  our  needs.  But  the 
forms,  positions,  distances,  and  extensions  of  bodies  are 
decisive  for  the  mode  and  the  quantity  of  the  satisfaction 
of  needs.  Mere  perception  by  itself  (estimation,  ocular 
measurement,  and  memory)  proves  to  be  too  much  under 
the  influence  of  physiological  circumstances  that  are  not 
easily  controlled,  for  us  to  build  securely  upon  it,  when 
the  question  is  one  of  judging  accurately  the  spatial 
relations  of  bodies  to  one  another.  We  are  therefore 
compelled  to  look  to  the  bodies  themselves  for  trust- 
worthy indications. 

Everyday  experience  brings  home  to  us  the  permanence 
of  bodies.  Under  ordinary  circumstances  this  permanence 
extends  also  to  particular  qualities,  such  as  color,  shape, 
and  size.  We  become  acquainted  with  rigid  bodies,  which, 
in  spite  of  their  mobility  in  space,  always  produce  the 
same  space-sensations  as  soon  as  they  are  brought  into  a 
definite  relation  with  our  body  and  are  seen  and  handled. 
Such  bodies  display  spatial  substantiality ; l  they  remain 
spatially  constant  and  identical.  One  rigid  body  A  may 
be  immediately  or  mediately  superimposed  spatially  on 
another  rigid  body  B,  or  on  parts  of  it,  and  this  relation 
remains  always  and  everywhere  the  same.  We  then  say 
B  is  measured  by  A.  When  bodies  are  compared  with 

1  It  is  certain  that  this  view  has  been  privately  held  by  innumerable 
geometricians.  It  comes  out  clearly  in  the  whole  arrangement  of 
Euclid's  geometry,  and  is  still  clearer  in  Leibniz,  particularly  in  his 
"geometrical  characteristic."  But  Helmholtz  was  the  first  to  discuss 
it  openly. 


192         THE  ANALYSIS  OF  SENSATIONS 

one  another  in  this  way,  the  question  is  no  longer  one 
as  to  the  kind  of  space-sensation  involved;  rather,  we 
have  a  judgment  as  to  their  identity  under  similar  circum- 
stances, and  this  judgment  is  formed  with  great  accuracy 
and  certainty.  Variations  in  the  results  of  measurement 
are,  in  fact,  negligible  in  comparison  with  the  element 
of  error  involved  in  immediate  spatial  judgments  as  to 
juxtaposed  or  successive  bodies,  and  it  is  in  this  fact  that 
the  advantage  and  the  rational  justification  of  the  process 
of  measurement  consist.  Instead  of  the  individual  hands  and 
feet,  which  everyone  carries  about  with  him  without  noticing 
any  appreciable  spatial  change  in  them,  a  universally  acces- 
sible standard  of  measure  is  soon  chosen,  which,  by  fulfilling 
in  a  high  degree  the  condition  of  immutability,  ushers  in  an 
era  of  greater  precision. 

8. 

The  object  of  all  geometrical  problems  is  to  establish 
a  numerical  correspondence  between  spaces  that  it  is 
required  to  ascertain  and  known  homogeneous  bodies. 
Empty  vessels  for  the  measurement  of  fluids,  or  of  com- 
pact aggregates  of  almost  exactly  similar  bodies,  are 
probably  the  oldest  measures.  The  volume  of  a  body, — 
the  aggregate  of  the  positions  occupied  by  its  matter, — 
which  we  instinctively  represent  to  ourselves  when  we 
look  at  or  grasp  some  body  with  which  we  are  familiar, 
comes  to  be  considered  as  a  quantum  of  material  properties 
that  satisfy  our  needs,  and  constitutes,  as  such,  an  object 
of  dispute.  Indeed,  originally  the  measurement  of  a  surface 
is  undertaken  solely  with  the  object  of  ascertaining  the 
amount  of  the  homogeneous  closely  juxtaposed  bodies 


THE  ANALYSIS  OF  SENSATIONS        193 

covering  the  surface.  Measurement  of  length, — that  is 
to  say,  enumeration  by  means  of  similar  pieces  of  string 
or  chain, — determines  the  minimum  volume  that  can  be 
interpolated  in  one  and  only  way  between  two  points, 
or  two  very  small  bodies.  If  in  this  process  we  abstract 
from  one  or  two  dimensions  of  the  bodies  used  as 
measures,  or,  again,  if  we  suppose  these  bodies  to  be 
everywhere  constant,  but  as  small  as  we  like  to  choose 
them,  we  arrive  at  the  idealized  representations  of  geometry. 


Our  intuition  of  space  is  enriched  by  experimenting  with 
material  objects,  owing  to  the  fact  that  metrical  experiences, 
which  spatial  intuition  would  not  be  able  to  acquire  by 
itself,  are  connected  with  these  objects.  Thus  we  become 
acquainted  with  the  metrical  properties  of  forms  with  which 
we  have  long  been  familiar,  such  as  the  straight  line,  the 
plane,  and  the  circle.  Again  it  is  experience,  as  history 
testifies,  which  has  first  led  to  the  knowledge  of  certain 
geometrical  propositions,  by  shewing  that,  if  an  object  has 
certain  dimensions,  certain  other  dimensions  of  it  were 
thereby  determined.  Scientific  geometry  set  itself  the 
economical  task  of  ascertaining  the  dependence  of  dimen- 
sions on  one  another,  of  avoiding  superfluous  measurements, 
and  of  discovering  the  simplest  geometrical  facts  from  which 
the  remaining  facts  would  follow  as  logical  consequences. 
For  this  purpose,  since  we  have  no  mental  control  over  nature, 
but  only  over  our  own  simple  logical  constructions,  our 
ultimate  geometrical  experiences  had  to  be  conceptually 
idealized.  Henceforth  there  was  no  obstacle  in  the  way  of 


i94        THE  ANALYSIS  OF  SENSATIONS 

the  discovery  of  geometrical  propositions  by  a  kind  of 
"thought-experiment," — by  advancing  along  the  road  of 
mental  visualization,  and  thinking  of  these  representations  as 
connected  with  the  idealized  geometrical  experiences.  The 
procedure  throughout  is  analogous  to  that  of  all  the  natural 
sciences.  But  the  ultimate  experiences  of  geometry  are 
reduced  to  so  small  a  minimum  that  is  only  too  easy  to 
overlook  them  altogether.  We  imagine  bodies  as  moving 
over  the  shadows  or  ghosts  of  bodies,  and  we  cling  mentally 
to  the  notion  that  their  measurements,  if  they  were  taken, 
would  not  be  altered  in  the  process.  Physical  bodies 
harmonize  with  the  results  in  so  far  as  they  are  sufficient  for 
the  presuppositions. 

Intuition,  physical  experiences,  and  conceptual  idealiza- 
tion, are,  therefore,  the  three  co-operating  factors  in 
scientific  geometry.  The  wide  divergence  in  the  views  of 
different  investigators  as  to  the  nature  of  geometry  is  due 
to  over — or  under — estimation  of  one  or  the  other  factor. 
The  only  possible  foundation  for  a  correct  view  is  the 
precise  separation  of  the  part  played  by  each  of  these  factors 
in  the  building  up  of  geometry.  For  instance,  our 
anatomically  symmetrical  motor  organization,  which  has 
been  acquired  for  purposes  of  rapid  locomotion,  causes  our 
intuition  to  make  the  two  halves  of  a  spatially  symmetrical 
construction  appear  to  us  as  equivalent ;  but  this  is  by  no 
means  true  from  a  physico-geometrical  point  of  view,  since 
they  cannot  be  brought  into  congruence.  Physically  they 
are  no  more  equivalent  than  a  movement  is  to  an  opposite 
movement,  or  a  rotation  to  a  rotation  in  the  opposite 
direction.  Kant's  paradoxes  on  this  subject  depend  on  an 
inadequate  separation  of  the  various  factors  involved. 


X.  THE  RELATIONS  OF  THE 
SIGHT-SENSATIONS  TO  ONE 
ANOTHER  AND  TO  OTHER 
PSYCHICAL  ELEMENTS. 

i. 

IN  normal  psychical  life,  sight-sensations  do  not  make 
their  appearance  alone,  but  are  accompanied  by  other 
sensations.  We  do  not  see  optical  images  in  an  optical 
space,  but  we  perceive  the  bodies  round  about  us  with  their 
many  and  varied  sensible  qualities.  Deliberate  analysis  is 
needed  to  single  out  the  sight-sensations  from  these  com- 
plexes. But  even  the  total  perceptions  themselves  are 
almost  invariably  accompanied  by  thoughts,  wishes,  and 
impulses.  By  sensations  are  excited,  in  animals,  the  move- 
ments of  adaptation  demanded  by  their  conditions  of  life. 
If  these  conditions  are  simple,  altering  but  little  and  slowly, 
immediate  sensory  excitation  is  sufficient.  Higher  intel- 
lectual development  is  unnecessary.  But  the  case  is 
different  where  the  conditions  of  life  are  intricate  and 
variable.  Here  so  simple  a  mechanism  of  adaptation  cannot 
develop,  still  less  would  it  lead  to  the  accomplishment  of 
the  required  ends. 

Lower  species  devour  everything  that  comes  in  their 
way  and  that  excites  the  proper  stimulus.  A  more  highly 
developed  animal  must  seek  its  food  at  risks  to  itself; 
when  found,  must  seize  it  at  the  right  spot,  or  capture  it  by 

195 


196        THE  ANALYSIS  OF  SENSATIONS 

cunning,  and  cautiously  test  its  character.  Long  trains  of 
varied  memories  must  pass  before  its  mind  before  one  is 
sufficiently  strong  to  outweigh  the  antagonistic  considera- 
tions and  to  excite  the  appropriate  movement.  Here, 
therefore,  a  sum  of  associated  remembrances  (or  experi- 
ences) coincidently  determining  the  adaptive  movements, 
must  accompany  and  confront  the  sensations.  In  this 
consists  the  intellect. 

In  the  young  of  higher  animals  under  complex  conditions 
of  life,  the  complexes  of  sensations  necessary  to  excite 
adaptive  movements  are  frequently  of  a  very  complicated 
nature.  The  sucking  of  young  mammals,  and  the  be- 
haviour of  the  young  sparrow  described  on  pp.  74,  75  are 
good  examples  of  this.  With  the  development  of  intelli- 
gence, the  parts  of  these  complexes  necessary  to  produce 
the  excitation  constantly  diminish,  and  the  sensations  are 
more  and  more  supplemented  and  replaced  by  the  intellect, 
as  may  be  daily  observed  in  children  and  adolescent  animals. 

In  a  note  to  the  edition  of  1886  I  uttered  a  warning 
against  the  tendency,  which  was  still  widespread  at  that 
time,  to  over-estimate  the  intelligence  of  the  lower  animals. 
My  view  was  based  solely  on  occasional  observations  on  the 
machine-like  movement  of  beetles,  the  flight  of  moths 
towards  the  light,  etc.  Subsequently  the  important  works 
of  J.  Loeb  appeared,  and  provided  a  solid  experimental 
basis  for  this  view. 

At  the  present  moment  (1906)  the  psychology  of  the 
lower  animals  has  again  become  the  field  of  much  contro- 
versy. While  A.  Bethe l  advocates  an  extreme  reflex-theory, 

1  A.  Bethe.  "  Diirfen  wir  den  Ameisen  und  Bienen  psychische 
Qualitaten  zuschreiben  ?  "  Pfliiger's  Archiv,  Vol.  LXX.,  p.  17;  "  Noch 


THE  ANALYSIS  OF  SENSATIONS        197 

based  on  ingenious  and  interesting  experiments  on  ants  and 
bees,  according  to  which  these  insects  are  to  be  regarded 
as  Cartesian  machines,  other  careful  critical  observers, 
such  as  E.  Wasmann,1  H.  von  Buttel-Reepen,2  and  A. 
Forel 3  ascribe  to  the  same  insects  a  high  degree  of  psychic 
development.  The  psychology  of  the  higher  animals  also 
has  lately  become  the  object  of  general  interest.  The 
writings  of  Theodor  Zell,  which  are  intended  principally 
for  the  general  public,  are  full  of  excellent  observation  and 
felicitous  insight,  and  seem  to  hit  with  great  caution  the 
proper  mean  between  over-estimating  and  under  estima- 
ting the  animals  of  which  they  treat. 

Anyone  who  has  studied  physiology,  or  even  anyone  who 
can  appreciate  the  work  of  F.  Goltz,  knows  the  very 
important  part  played  by  reflexes  in  preserving  the  life  of 
all  animal  organisms,  even  of  the  human  organism,  which 
is  the  most  highly  developed  of  all.  To  anyone,  again, 
who  has  observed  the  striking  way  in  which  the  influence 
exercised  upon  the  biological  reactions  by  a  memory  that 

einmal  fiber  die  psychischen  Qualitaten  der  Ameisen,"  Ibid,,  Vol. 
LXXIX.,  p.  39  ;  Beer,  Be  the  and  Uexkiill,  "  Vorschlage  zu  einer  objek- 
tivierenden  Nomenklatur  in  der  Physiologic  des  Nervensystems," 
Centralblatt  far  Physiologic,  1899,  Vol.  XIII.,  No.  6;  H.  E.  Hering, 
"  Inwiefern  ist  es  moglich  die  Physiologic  von  der  Psychologic  sprach- 
lich  zu  trennen?"  Detitsche  Arbeit,  ist  year,  No.  12. 

1  E.  Wasmann,  Die  psychischen  Fiihigkeiten  der  Ameisen,  Stuttgart 
1899  (Zoologica,  No.  26)  ;    Vergleichende  Studien  Uber  das  Seelenleben 
der    Ameisen  ttnd   der  hb'heren    Tiere,    2nd    edition,    Freiburg    im 
Breisgau,  1900. 

2  H.  v.  Buttel-Reepen,  Sind  die  Bienen  Reflexmaschinen?,  Leipzig-, 
1900. 

3  A.  Forel,  "  Psychische  Fahigkeiten  der  Ameisen,"  Transactions  of 
the  Fifth  International  Zoological  Congress,  Jena,  1902  ;  "  Experiences 
et  remarques   critiques  sur  les  sensations  des  insectes,"  Rivista  di 
Scienze  Biologiche,  Como,  19001. 


198        THE  ANALYSIS  OF  SENSATIONS 

registers  the  experiences  of  the  individual,  decreases  with 
the  simplification  of  the  organism,  it  will  naturally  occur 
to  try  whether  and  to  what  extent  the  behaviour  of  simpler 
organisms  can  be  explained  solely  by  reference  to  reflexes.1 
It  is  not,  indeed,  probable  that  there  exist  any  animal 
organisms  entirely  devoid  of  memory  and  endowed  with 
reflexes  absolutely  incapable  of  modification,  since  it  is 
scarcely  possible  to  draw  a  sharp  line  between  the  acquisi- 
tions of  the  species  and  the  acquisitions  of  the  individual.2 
Still,  I  should  consider  such  an  attempt  as  well  worth 
making,  although  a  critical  analysis  of  the  result  would  be 
still  more  valuable. 

I  hope  that  we  shall  still  learn  a  great  deal  for  our  own 
psychology,  not  only  from  our  children,  but  also  from  "  our 
younger  brothers1'  the  animals.  But  in  order  to  under- 
stand why  man  is  psychically  so  much  more  than  the 
cleverest  animal,  it  will  be  sufficient  to  reflect  on  the 
acquisitions  which  the  individual  and  the  species  have 
made  in  the  atmosphere  of  a  social  culture  extending  over 
many  thousand  years. 


Representation  by  images  and  ideas,  therefore,  has  to 
supply  the  place  of  sensations,  where  the  latter  are  im- 
perfect, and  to  carry  to  their  issue  the  processes  initially 
determined  by  sensations  alone.  But  in  normal  life, 
representation  cannot  permanently  supplant  sensation, 

1  Mach,  Populdr-wissenchaftliche  Vorlesungen,  "  Ueber  den  Einfluss 
zufalliger  Umstande,"  etc. ,  Leipzig,  1903,  3rd  edition,  pp.  294-295; 
Prinzipien  der    Wdrmelehre,    Leipzig,    1900.       See    the   chapter   on 
"  Sprache  und  Begriffe." 

2  Cf.  the  fourth  edition  of  this  work,  p.  153. 


THE  ANALYSIS  OF  SENSATIONS        199 

where  this  is  at  all  present,  except  with  the  greatest  danger 
to  the  organism.  As  a  fact,  there  is,  in  normal  psychical 
life,  a  marked  difference  between  the  two  species  of 
psychical  elements.  I  see  a  blackboard  before  me.  I 
can,  with  the  greatest  vividness,  represent  to  myself  on 
this  blackboard,  either  a  hexagon  drawn  in  clear,  white 
lines,  or  a  colored  figure.  But,  pathological  cases  apart, 
I  always  distinguish  what  I  see  and  what  I  represent  to 
myself.  In  the  transition  to  mental  imagery,  I  am  aware 
that  my  attention  is  turned  from  my  eyes,  and  directed 
elsewhere.  In  consequence  of  this  attention,  the  spot  seen 
upon  the  blackboard  and  the  one  represented  to  myself  as 
situated  in  the  same  place  differ  as  by  a  fourth  co-ordinate. 
It  would  not  be  a  complete  description  of  the  facts  to  say 
that  the  image  is  superimposed  on  the  object  as  the  images 
reflected  in  a  transparent  plate  of  glass  are  superimposed 
on  the  bodies  seen  through  it.  On  the  contrary,  what  is 
represented  seems  to  me  to  be  supplemented  by  a  qualita- 
tively different  and  opposite  sensational  stimulus,  which 
stimulus  it  in  its  turn  sometimes  supplants.  We  are  con- 
fronted here,  for  the  time  being,  with  a  psychological  fact, 
the  physiological  explanation  of  which  will  sometime 
undoubtedly  be  discovered. 

It  is  natural  to  suppose  that,  when  mental  images  occur, 
the  interaction  of  the  organs  of  the  nervous  system  causes 
the  repetition  of  organic  processes  partially  identical  with 
those  which  were  determined  by  the  physical  stimulus 
on  occasion  of  the  corresponding  sensations.  Images 
are  normally  distinguished  from  sensations  by  being  less 
intense,  and  above  all  by  their  instability.  When  I  draw 
a  geometrical  figure  in  imagination,  it  is  as  if  the  lines  faded 


200        THE  ANALYSIS  OF  SENSATIONS 

immediately  after  they  are  drawn,  as  soon  as  my  attention 
is  directed  to  ether  lines :  when  one  comes  back  to  them 
they  have  vanished,  and  must  be  reproduced  over  again. 
This  is  the  principal  reason  of  the  advantage  in  point  of 
convenience  which  an  actual  material  geometrical  drawing 
possesses  over  a  merely  imagined  one.  It  is  easy  enough 
to  hold  firmly  before  the  mind  a  small  number  of  lines,  for 
instance  an  arc  of  a  circle  with  the  angles  at  the  centre  and 
circumference  and  a  pair  of  coincident  or  intersecting  sides  ; 
but  if  in  this  case  we  proceed  to  add  the  diameter  drawn 
through  the  apex  of  the  angle  at  the  circumference,  it  at 
once  becomes  more  difficult  to  deduce  in  imagination  the 
relative  sizes  of  the  angles,  without  continually  renewing  and 
completing  the  figure.  The  power  of  replacing  the  figure 
with  ease  and  rapidity,  is,  however,  enormously  increased  by 
practice.  When  I  was  studying  the  geometry  of  Steiner 
and  Von  Staudt,  I  was  able  to  do  this  to  a  much  greater 
extent  than  I  can  now. 

Where  the  development  of  intelligence  has  reached  a  high 
point,  such  as  is  presented  now  in  the  complex  conditions 
of  human  life,  mental  images  may  frequently  absorb  the 
whole  of  attention,  so  that  events  in  the  neighbor- 
hood of  the  reflecting  person  are  not  noticed,  and 
questions  addressed  to  him  are  not  heard ;  —  a  state 
which  persons  unused  to  it  are  wont  to  call  absent- 
mindedness,  although  it  might  with  more  appropriate- 
ness be  called  present-mindedness.  If  the  person  in 
question  is  disturbed  in  such  a  state,  he  has  a  very 
distinct  sensation  of  the  labor  involved  in  the  transference 
of  his  attention. 


THE  ANALYSIS  OF  SENSATIONS        201 


It  is  well  to  note  this  sharp  division  between  images 
and  sensations,  as  it  is  an  excellent  safeguard  against 
carelessness  in  psychological  explanations  of  sense-pheno- 
mena. The  well-known  theory  of  "  unconscious  inferences  " 
would  never  have  reached  its  present  extended  development 
if  more  heed  had  been  paid  to  this  circumstance. 

The  organ,  of  which  the  states  determine  images,  can 
provisionally  be  conceived  as  one  which,  in  a  diminished 
degree,  is  capable  of  all  the  specific  energies  of  the  sense 
and  motor  organs,  so  that  the  specific  energy  now  of  one, 
now  of  another,  sense-organ  can  play  upon  it,  according  to 
the  nature  and  direction  of  its  attention  for  the  time  being. 
Such  an  organ  is  eminently  qualified  to  effect  physiological 
relations  between  the  different  energies.  As  is  shewn  by 
experiments  with  animals  whose  cerebrum  has  been  re- 
moved, there  are  probably,  in  addition  to  the  organ  of 
representation,  a  number  of  other  analogous  organs  of 
mediation,  which  are  less  intimately  connected  with  the 
cerebrum,  and  whose  processes  consequently  do  not  appear 
in  consciousness. 

That  wealth  of  representative  life  with  which  we  are 
personally  acquainted  from  self-observation,  doubtless  made 
its  first  appearance  with  man.  But  the  beginnings  of  this 
expression  of  life,  in  which  nothing  but  the  relations  of  the 
various  parts  of  the  organism  to  one  another  is  manifested, 
go  back  with  no  less  certainty  to  quite  primitive  stages  in 
the  animal  scale.  But  the  parts  of  single  organs  must  also, 
in  virtue  of  their  reciprocal  tension,  stand  to  one  another 
in  a  relation  analogous  to  that  in  which  the  parts  of  the 


202         THE  ANALYSIS  OF  SENSATIONS 

organism  as  a  whole  stand  to  one  another.  The  two 
retinae,  with  their  motor  mechanism  of  accommodation 
and  of  luminous  adjustment,  dependent  on  light-sensations, 
afford  a  very  clear  and  familiar  example  of  such  a  relation. 
Physiological  experiment  and  simple  self-observation  teach 
us  that  such  an  organ  has  its  own  purposive  habits,  its  own 
peculiar  memory,  one  might  almost  say  its  own  intelligence. 


The  most  instructive  observations  in  this  connexion  are 
probably  those  of  Johannes  Miiller,  collected  in  his  admir- 
able work  on  "  The  Phantasms  of  Sight  "  ( Ueber  diephantas- 
tischen  Gesichtserscheinungen,  Coblenz,  1826).  The  sight- 
phantasms  observed  by  Miiller  and  others  in  the  waking 
state  are  entirely  withdrawn  from  the  influence  of  either 
the  will  or  the  reason.  They  are  independent  phenomena, 
essentially  connected  with  the  sense-organs,  and  charac- 
terized by  complete  visual  objectivity.  They  are  veritable 
imagination-  and  memory-phenomena  of  sense.  Miiller 
considers  that  the  free  individual  existence  of  hallucinations 
is  a  part  of  the  life  of  the  organism,  and  that  it  cannot  be 
brought  under  the  so-called  laws  of  association,  in  which 
he  indicates  that  he  does  not  believe.  It  seems  to  me  that 
the  continuous  alteration  of  the  phantasms,  as  described  by 
him,  is  no  evidence  against  the  laws  of  association.  These 
processes  can,  on  the  contrary,  be  conceived  as  recollec- 
tions of  slow  perspectival  changes  in  visual  images.  The 
element  of  desultoriness  in  the  common  connexion  of 
a  train  of  representations  by  way  of  association,  only 
comes  in  when  sometimes  one,  and  sometimes  another, 


THE  ANALYSIS  OF  SENSATIONS        203 

department  of  sensation  begins  to  be  involved  (see 
Chapter  XL) 

Those  processes  which  (according  to  Miiller)  are  normally 
induced  in  the  "visual  substance"  by  excitations  of  the 
retina,  and  which  condition  the  act  of  seeing,  may  also, 
under  exceptional  conditions,  be  spontaneously  produced 
in  the  visual  substance  without  excitation  of  the  retina,  and 
thus  become  the  source  of  phantasms  or  hallucinations. 
We  speak  of  sense-memory  when  the  phantasms  are  closely 
allied  in  character  to  objects  seen  before,  of  hallucinations 
when  the  phantasms  arise  more  freely  and  independently. 
But  no  sharp  distinction  between  the  two  cases  can  be 
maintained. 

I  am  acquainted  with  all  manner  of  sight-phantasms  from 
my  own  experience.  The  mingling  of  phantasms  with 
objects  indistinctly  seen,  the  latter  being  partly  supplanted, 
is  probably  the  most  common  case.  In  my  own  case,  these 
phenomena  are  particularly  vivid  after  a  tiring  night's 
journey  in  the  train.  Rocks  and  trees  then  assume  the 
most  fantastic  shapes.  Years  ago,  while  engrossed  with  the 
study  of  pulse-tracings  and  sphygmography,  the  fine  white 
curves  on  the  dark  background  often  came  up  before  my 
eyes,  in  the  evening  or  in  the  dim  light  of  day,  with  the  full 
semblance  of  reality  and  objectivity.  Later  also,  during 
miscellaneous  work  in  physics,  I  witnessed  analogous 
phenomena  of  "sense-memory."  More  rarely,  images  of 
things  which  I  have  never  seen  before,  have  appeared  before 
my  eyes  in  the  daytime.  Thus,  years  ago,  on  a  number 
of  successive  days,  a  bright  red  capillary  net  (similar  to 
a  so-called  enchanted  net)  shone  out  upon  the  book  in 
which  I  was  reading,  or  on  my  writing  paper,  although 


204        THE  ANALYSIS  OF  SENSATIONS 

I  had  never  been  occupied  with  forms  of  this  sort.  The 
sight  of  bright-colored  changing  carpet  patterns  before  falling 
asleep  was  very  familiar  to  me  in  my  youth ;  the  pheno- 
menon will  still  make  its  appearance  if  I  fix  my  atten- 
tion on  it.  One  of  my  children,  likewise,  often  used 
to  tell  me  that  he  "  saw  flowers "  before  falling  asleep. 
Less  often,  I  see  in  the  evening,  before  falling  asleep, 
various  human  figures,  which  alter  without  the  action 
of  my  will.  On  a  single  occasion  I  attempted  suc- 
cessfully to  change  a  human  face  into  a  fleshless  skull; 
this  solitary  instance  may,  however,  be  an  accident. 
It  has  often  happened  to  me  that,  on  awaking  in  a 
dark  room,  the  images  of  my  latest  dreams  remained 
present  in  vivid  colors  and  in  abundant  light.  A 
peculiar  phenomenon,  which  has  for  some  years  frequently 
occurred  with  me,  is  the  following.  I  awake  and  lie 
motionless  with  my  eyes  closed.  Before  me  I  see  the  bed- 
spread with  all  its  little  folds,  and  upon  it,  motionless  and 
unchanging,  my  hands  in  all  their  details.  If  I  open  my 
eyes,  either  it  is  quite  dark,  or  it  is  light,  but  the  bed-spread 
and  my  hands  lie  quite  differently  from  the  manner  in 
which  they  appeared  to  me.  This  is  a  remarkably  fixed  and 
persistent  phantasm  with  me,  such  as  I  have  not  observed 
under  other  conditions.  As  regards  this  image,  I  think  that  I 
notice  that  all  its  parts,  even  those  that  are  widely  separated, 
appear  with  equal  distinctness  in  a  way  which  for  obvious 
reasons  is  impossible  in  the  case  of  anything  objectively  seen. 
When  I  was  young  I  used  frequently  to  have  very  vivid 
acoustic,  and  particularly  musical,  hallucinations  on  waking 
up ;  they  have,  however,  become  extremely  rare  and  faint 
since  my  interest  in  music  has  decreased.  But  perhaps 


THE  ANALYSIS  OF  SENSATIONS        205 

the  interest  in  music  is  itself  a  secondary  effect,  rather 
than  a  cause. 

When  we  withdraw  the  retina  from  the  influence  of 
outward  excitations,  and  turn  the  attention  to  the  field  of 
vision  alone,  traces  of  phantasms  are  almost  always  present. 
Indeed,  they  make  their  appearance  when  the  outer 
excitations  are  merely  weak  and  indistinct,  in  a  half-light, 
or  when  we  look  at  a  surface  covered  with  dim,  blurred 
spots,  such  as  a  cloud,  or  a  grey  wall.  The  figures  which 
we  then  seem  to  see,  provided  they  are  not  produced  by  a 
direct  act  of  attention  in  selecting  and  combining  distinctly 
seen  spots,  are  certainly  not  products  of  representation, 
but  constitute,  at  least  in  part,  spontaneous  phantasms, 
which,  for  the  time  being  and  at  some  points,  take  forcible 
precedence  over  the  retinal  excitation.  In  these  cases 
expectation  seems  to  be  favorable  to  the  occurrence  of 
the  phantasms.  When  I  have  been  looking  for  interfer- 
ence-bands I  have  very  often  thought  that  I  could  clearly 
detect  the  first  dull  traces  of  them  in  the  field  of  vision, 
when  the  progress  of  the  experiment  has  convinced  me 
that  I  was  certainly  deluded.  Over  and  over  again,  in  a 
half-light,  I  have  thought  that  I  could  distinctly  see  a  jet 
of  water  that  I  was  expecting  to  come  out  of  an  india- 
rubber  tube,  and  have  had  to  touch  with  my  finger  to 
convince  myself  of  my  mistake.  Such  weak  phantasms 
seem  as  a  rule  to  yield  readily  to  the  influence  of  the 
intellect,  whereas  the  intellect  is  unable  to  produce  any 
effect  on  strong  phantasms  with  vivid  colors.  The  former 
are  more  akin  to  representations,  the  latter  to  sensations. 

These    weak    phantasms,    which    are    sometimes   over- 
powered   by   sensations,    are    sometimes    in   equilibrium 


206        THE  ANALYSIS  OF  SENSATIONS 

with  them,  and  sometimes  replace  them,  suggest  the 
possibility  of  comparing  the  strength  of  phantasms  with 
the  strength  of  sensations.  Scripture  has  carried  out  this 
idea.  He  takes  an  observer  who  thinks  that  he  sees  a 
colored  cross,  which  is  really  non-existent,  and  then  causes 
to  appear  in  his  field  of  vision  a  real  line  of  intensity 
increasing  from  zero  upwards  and  drawn  in  a  direction 
which  is  not  known  beforehand,  until  the  line  is  noticed 
and  given  the  same  value  as  the  phantasm.1  In  this  way 
all  the  transitional  stages  between  sensation  and  representa- 
tion can  be  obtained.  At  no  point  do  we  come  upon  a 
psychical  element  that  is  absolutely  incapable  of  being 
compared  with  the  sensation,  which  we  must  undoubtedly 
regard  as  a  physical  object  also.  The  way  in  which  the 
presentations  are  connected  by  association  is,  however, 
quite  different  from  the  way  in  which  the  sensations  are 
connected. 


Leonardo  da  Vinci  discusses  the  mingling  of  phantasms 
with  objects  seen  (see  p.  66  above)  in  the  following  words  : 

"  I  shall  not  omit  to  give  a  place  among  these  directions 
to  a  newly-discovered  sort  of  observation,  which  may, 
indeed,  make  a  small  and  almost  ludicrous  appearance,  but 
which  is,  nevertheless,  very  useful  in  awakening  the  mind 
to  various  discoveries.  It  consists  in  this,  that  thou 
shouldst  regard  various  walls  which  are  covered  with  all 
manner  of  spots,  or  stone  of  different  composition.  If 
thou  hast  any  capacity  for  discovery,  thou  mayest  behold 
there  things  which  resemble  various  landscapes  decked 
1  Scripture,  The  New  Psychology,  London,  1897,  p.  484. 


THE  ANALYSIS  OF  SENSATIONS        207 

with  mountains,  rivers,  cliffs,  trees,  large  plains,  hills  and 
valleys  of  many  a  sort.  Thou  canst  also  behold  all 
manner  of  battles,  life-like  positions  of  strange,  unfamiliar 
figures,  expressions  of  face,  costumes,  -  and  numberless 
things  which  thou  mayest  put  into  good  and  perfect  form. 
The  experience  with  regard  to  walls  and  stone  of  this  sort 
is  similar  to  that  of  the  ringing  of  bells,  in  the  strokes  of 
which  thou  willst  find  anew  every  name  and  every  word 
that  thou  mayest  imagine  to  thyself. 

"  Do  not  despise  this  opinion  of  mine  when  I  counsel 
thee  sometimes  not  to  let  it  appear  burdensome  to  thee  to 
pause  and  look  at  the  spots  on  walls,  or  the  ashes  in  the 
fire,  or  the  clouds,  or  mud,  or  other  such  places;  thou 
wilt  make  very  wonderful  discoveries  in  them,  if  thou 
observest  them  rightly.  For  the  mind  of  the  painter  is 
stimulated  by  them  to  many  new  discoveries,  be  it  in  the 
composition  of  battles,  of  animals  and  human  beings,  or 
in  various  compositions  of  landscapes,  and  of  monstrous 
things,  as  devils  and  the  like,  which  are  calculated  to  bring 
thee  honor.  For  through  confused  and  undefined  things 
the  mind  is  awakened  to  new  discoveries.  But  take  heed, 
first,  that  thou  understandest  how  to  shape  well  all  the 
members  of  the  things  that  thou  wishest  to  represent,  for 
instance,  the  limbs  of  living  beings,  as  also  the  parts  of  a 
landscape,  namely  the  stones,  trees,  and  the  like." 

All  marked  and  independent  appearance  of  phantasms 
without  excitation  of  the  retina — dreams  and  the  half- 
waking  state  excepted — must,  by  reason  of  their  biological 
purposelessness,  be  accounted  pathological.  In  like 
manner,  we  are  constrained  to  regard  every  abnormal 
dependence  of  phantasms  upon  the  will  as  pathological. 


208        THE  ANALYSIS  OF  SENSATIONS 

Such,  very  likely,  are  the  states  that  occur  in  insane 
persons  who  regard  themselves  as  very  powerful,  as  God, 
etc.  But  the  delusions  of  the  megalo-maniac  can  equally 
be  produced  by  the  mere  absence  of  inhibitory  associations ; 
for  instance,  one  can  believe  in  a  dream  that  one  has  solved 
the  most  tremendous  problems,  because  the  associations 
that  reveal  the  contradiction  do  not  take  place. 


6. 

After  these  introductory  remarks  we  may  now  turn  to  the 
consideration  of  a  few  physiologico-optical  phenomena,  the 
full  explanation  of  which,  it  is  true,  is  still  distant,  but  which 
are  best  understood  as  the  expressions  of  an  independent 
life  on  the  part  of  the  sense-organs. 

We  usually  see  with  both  eyes,  and  agreeably  to  definite 
needs  of  life,  not  colors  and  forms,  but  bodies  in  space.  It 
is  not  the  elements  of  the  complex,  but  the  whole  physio- 
logico-optical complex  that  is  of  importance.  This  complex 
the  eye  seeks  to  fill  out  and  supplement,  according  to  the 
habits  acquired  (or  inherited)  in  its  environment,  whenever, 
as  a  result  of  special  circumstances,  the  appearance  of  the 
complex  is  incomplete.  This  occurs  oftenest  in  monocular 
vision,  but  is  also  possible  in  the  binocular  observation  of 
very  distant  objects  where  the  stereoscopic  differences  con- 
sequent upon  the  distance  of  the  eyes  from  each  other  vanish. 

We  generally  perceive,  not  light  and  shadow,  but  objects 
in  space.  The  shading  of  bodies  is  scarcely  noticed. 
Differences  in  brightness  produce  differences  in  the  sensa- 
tion of  depth,  and  help  to  produce  the  modelling  of  bodies 
when  the  stereoscopic  differences  are  insufficient  for  this 


THE  ANALYSIS  OF  SENSATIONS        209 

purpose, — a    condition   which   is   very   noticeable   in   the 
observation  of  distant  mountains. 

Very  instructive,  from  this  point  of  view,  is  the  image  on 
the  dull  plate  of  the  photographic  camera.  We  are  often 
astounded  at  the  brightness  of  the  lights  and  the  depth  of  the 
shadows,  which  were  not  noticed  in  the  bodies  themselves  as 
long  as  one  was  not  compelled  to  see  everything  in  a  single 
plane.  I  remember  quite  well  that,  in  my  childhood,  all 
shading  of  a  drawing  appeared  to  me  an  unjustifiable 
disfigurement,  and  that  an  outline-drawing  was  much  more 
satisfactory  to  me.  It  is  likewise  well  known  that  whole 
peoples,  for  instance  the  Chinese,  despite  a  well-developed 
artistic  technique,  do  not  shade  at  all,  or  shade  only  in  a 
defective  manner. 

The  following  experiment,  which  I  made  many  years 
ago,1  illustrates  very  clearly  the  relation  in  question  between 
the  sensation  of  light  and  the  sensation  of  depth. 
We  place  a  visiting-card,  bent  crosswise  before 
us  on  the  desk,  so  that  its  bent  edge  b  e  is  to- 
wards us.  Let  the  light  fall  from  the  left.  The 
half  abdev$>  then  much  lighter,  the  \\d\ibcef  l 
much  darker — a  fact  which  is,  however,  scarcely 
perceived  in  unprejudiced  observation.  We  now 
close  one  eye.  Hereupon,  part  of  the  space-sensations  dis- 
appear. Still  we  see  the  bent  card  spatially  and  nothing 
noticeable  in  the  illumination.  But  as  soon  as  we  succeed 
in  seeing  the  bent  edge  depressed  instead  of  raised,  the  light 
and  the  shade  stand  out  as  if  painted  thereon.  I  pass  over 
for  the  moment  the  perspectival  reversal  of  the  card,  which 

1  "  Ueber  die  physikalische  Wirkung  raumlich  verteilter  Lichtreize," 
Sitzungsbcrichte  der  Wiener  Akademie^  Vol.  LIV.,  October  1866. 
0 


210        THE  ANALYSIS  OF  SENSATIONS 


can  easily  be  explained.  Such  an  "  inversion  "  is  possible, 
because  depth  is  not  determined  by  a  monocular  image.  If 
in  Fig.  25,  i  O  represents  the  eye,  a  b  c  a  section  of  a  bent 
card,  and  the  arrow  the  direction  of  the  light,  ab  will 
appear  lighter  than  be.  Also  in  2,  a  b  will  appear  lighter 
than  b  c.  Plainly,  the  eye  must  acquire  the  habit  of  varying 
the  fall  in  the  sensation  of  depth  concomitantly  with  the 
change  in  brightness  of  the  surface-elements  that  it  sees. 
The  fall  and  the  depth  diminish,  with  diminishing  illumina- 
tion, towards  the  right,  when 
the  light  falls  from  the  left  (i) ; 
contrariwise,  when  it  falls  from 
the  right.  Since  the  wrappings 
of  the  bulb  in  which  the  retina 
is  embedded  are  translucent,  it 
is  not  a  matter  of  indifference 
for  the  distribution  of  light 
upon  the  retinae  whether  the 
light  falls  from  the  right  or  the 
left.  Accordingly,  things  are  so 

arranged  that,  without  any  aid  of  the  judgment,  a  fixed 
habit  of  the  eye  is  developed,  by  means  of  which  illumina- 
tion and  depth  are  connected  in  a  definite  way.  If  now,  by 
virtue  of  another  habit,  it  is  possible  to  bring  a  part  of  the 
retina  into  conflict  with  the  first  habit,  as  in  the  above  experi- 
ment, the  effect  is  made  manifest  in  remarkable  sensations. 
Certain  experiments  of  Fechner's  have  shewn  how  im- 
portant the  effect  of  the  light  that  penetrates  through  the 
wrappings  of  the  bulb  can  become.1  One  observation  in 

1  Feclmer,    "  Ueber  den  seitlichen    Fenster-  und   Kerzenversuch," 
Berichte  der  Leipziger  Gesellschaft  der  Wissensckaf/en,  1860. 


Fig.  25. 


THE  ANALYSIS  OF  SENSATIONS        211 

this  connexion  is  as  follows.  Beneath  my  writing-table 
is  a  grey-green  rug,  a  small  piece  of  which  I  can  see  as 
I  write.  Now,  when  a  double  image  of  this  bit  arises, 
accidentally  or  intentionally,  when  the  sunlight  or  daylight 
comes  from  the  left,  the  image  belonging  to  the  left,  or 
more  strongly  illuminated  eye,  is  a  vivid  green  by  contrast, 
while  the  image  on  the  right  side  is  quite  dull  in  color. 
It  would  be  interesting  to  study  the  variation  of  intensity 
and  color  of  the  illumination  of  the  bulb  in  the  case  of 
these  images  and  in  experiments  in  inversion. 

The  purpose  of  the  preceding  remarks  is  merely  to 
point  out  the  character  of  the  phenomenon  under  con- 
sideration and  to  indicate  the  direction  in  which  a  physio- 
logical explanation  (exclusive  of  psychological  speculation) 
is  to  be  sought.  We  will  further  remark  that,  with  respect 
to  interchangeable  qualities  of  sensation,  a  principle  similar 
to  that  of  the  conservation  of  energy  seems  to  hold. 
Differences  of  brightness  are  partly  transformed  into  differ- 
ences of  depth,  and  themselves  become  weaker  in  the 
process.  At  the  expense  of  differences  of  depth,  on 
the  other  hand,  differences  of  brightness  may  be 
augmented.  An  analogous  observation  will  be  made 
later  on  in  another  connexion. 


The  habit  of  observing  bodies  as  such,  that  is,  of  giving 
attention  to  a  large  and  spatially  cohering  mass  of  light- 
sensations,  is  the  cause  of  peculiar  and  often  surprising 
phenomena.  A  two-colored  painting  or  drawing,  for 
instance,  appears  in  general  quite  different  according  as  we 


212        THE  ANALYSIS  OF  SENSATIONS 


take  the  one  or  the  other  color  as  the  background.     The 
puzzle  pictures,  in  which,  for  example,  an  apparition  makes 

its  appearance  between  tree- 
trunks  as  soon  as  the  dark 
trees  are  taken  as  the  back- 
ground, and  the  bright  sky  as 
the  object,  are  well  known. 
In  exceptional  instances  only 
do  background  and  object 
possess  the  same  form  —  a 
configuration  frequently  em- 
ployed in  ornamental  designs, 
as  may  be  seen  in  Fig. 
26,  taken  from  p.  15  of  the 
above  -  mentioned  Grammar 
of  Ornament^  also  in  Figs.  20 
and  22  of  Plate  45,  and  in 
Fig.  13  of  Plate  43  of  that  work. 


Pig.  26. 


The  phenomena  of  space-vision  which  accompany  the 
monocular  observation  of  a  perspective  drawing,  or,  what 
amounts  to  the  same  thing,  the  monocular  observation  of 
an  object,  are  generally  very  lightly  passed  over,  as  being 
self-evident  in  nature.  But  I  am  of  the  opinion  that  there 
is  yet  much  to  be  investigated  in  these  phenomena.  One 
and  the  same  image  in  perspective  may  represent  an 
unlimited  number  of  different  objects,  and  consequently 
the  space-sensation  can  be  only  in  part  determined  by  such 
a  drawing.  If,  therefore,  despite  the  many  bodies  conceiv- 


THE  ANALYSIS  OF  SENSATIONS        213 

able  as  belonging  to  the  figure,  only  a  few  are  really  seen 
with  the  full  character  of  objectivity,  there  must  exist  some 
good  physiological  reason  for  the  fact.  It  cannot  arise  from 
the  adducing  of  auxiliary  considerations  in  thought,  nor  from 
the  awakening  of  conscious  remembrances  in  any  form,  but 
must  depend  on  certain  organic  life  habits  of  the  visual  sense. 
If  the  visual  sense  acts  in  conformity  with  the  habits 
which  it  has  acquired  under  the  conditions  of  life  of  the 
species  and  the  individual,  we  may,  in  the  first  place, 
assume  that  it  proceeds  according  to  the  principle  of  prob- 
ability ;  that  is,  those  functions  which  have  been  most 
frequently  excited  together  before,  will  afterwards  tend  to 
make  their  appearance  together  when  only  one  is  excited. 
For  example,  those  particular  sensations  of  depth  which  in 
the  past  have  been  most  frequently  associated  with  a  given 
perspective  figure,  will  be  readily  reproduced  again  when 
that  figure  makes  its  appearance,  although  not  necessarily 
co-determined  thereby.  Furthermore,  a  principle  of 
economy  appears  to  manifest  itself  in  the  observation  of 
perspective  drawings  ;  that  is  to  say,  the  visual  sense  never 
of  itself  burdens  itself  with  any  greater  effort  than  is 
demanded  by  the  stimulus.  The  two  principles  coincide 
in  their  effects,  as  we  shall  presently  see. 


The  following  may  serve  as  a  detailed  illustration  of  the 
above.  When  we  look  at  a  straight  line  in  a  perspective 
drawing,  we  always  see  it  as  a  straight  line  in  space, 
although  the  straight  line,  qua  perspective  drawing,  may 
correspond  to  an  unlimited  number  of  different  plane 


214        THE  ANALYSIS  OF  SENSATIONS 

curves,  qua  objects.  But  only  in  the  special  case  where 
the  plane  of  a  curve  passes  through  the  centre  of  one 
eye,  will  it  be  reproduced  on  the  retina  in  question  as  a 
straight  line  (or  as  a  great  circle),  and  only  in  the  yet  more 
special  case  where  the  plane  of  the  curve  passes  through 
the  centres  of  both  eyes,  will  it  be  reproduced  as  a  straight 
line  for  both  eyes.  It  is  thus  extremely  improbable  that  a 
plane  curve  should  ever  appear  a  straight  line,  while  on  the 
other  hand  a  straight  line  in  space  is  always  reproduced  on 
both  retinae  as  a  straight  line.  The  most  probable  object, 
therefore,  answering  to  a  straight  line  in  perspective,  is  a 
straight  line  in  space. 

The  straight  line  has  various  geometrical  properties. 
But  these  geometrical  properties,  for  example  the  familiar 
characteristic  of  being  the  shortest  distance  between  two 
points,  are  not  physiologically  of  importance.  It  is  of 
far  more  consequence  that  straight  lines  lying  in  the 
median  plane  or  perpendicular  thereto  are  physiologically 
symmetrical  to  themselves.  A  vertical  lying  in  the  median 
plane  is  also  physiologically  distinguished  by  its  perfect 
uniformity  of  depth-sensation,  and  by  its  coincidence  with 
the  direction  of  gravity.  All  vertical  straight  lines  may  be 
readily  and  quickly  made  to  coincide  with  the  median  plane, 
and  consequently  partake  of  this  physiological  advantage. 
But  the  spatial  straight  line  generally,  must  be  physiologi- 
cally distinguished  by  some  further  mark.  Its  sameness  of 
direction  in  all  its  elements  has  already  been  pointed  out. 
In  addition  to  this,  however,  it  is  to  be  noted  that  every 
point  of  a  straight  line  in  space  marks  the  mean  of  the 
depth-sensations  of  the  neighboring  points.  Thus  the 
straight  line  in  space  gives  a  minimum  of  departure  from 


THE  ANALYSIS  OF  SENSATIONS        215 

the  mean  of  the  depth-sensations,  just  as  every  point  on 
the  straight  line  gives  the  mean  of  the  similar  space-values 
of  the  adjacent  points;  and  the  assumption  forthwith 
presents  itself  that  the  straight  line  is  seen  with  the  least 
effort.  The  visual  sense  acts  therefore  in  conformity  with 
the  principle  of  economy,  and,  at  the  same  time,  in  con- 
formity with  the  principle  of  probability,  when  it  exhibits 
a  preference  for  straight  lines. 

As  early  as  1866,  I  wrote,  in  the  Proceedings  of  the 
Vienna  Academy ',  Vol.  54 :  "  Since  straight  lines  every- 
where surround  civilized  human  beings,  we  may,  I  think, 
assume,  that  every  straight  line  which  can  possibly  be 
produced  upon  the  retina  has  been  seen  numberless  times, 
in  every  possible  way,  spatially  as  a  straight  line.  The 
efficiency  of  the  eye  in  the  interpretation  of  straight  lines 
ought  not,  therefore,  to  astonish  us."  Even  then  I  wrote 
this  passage  (opposing  the  Darwinian  view,-  which  I  sup- 
ported in  the  same  paper)  half-heartedly.  To-day  I  am 
more  than  ever  convinced  that  the  efficiency  referred  to 
is  not  the  result  of  individual  practice,  nor  indeed  of 
human  practice  at  all,  but  that  it  is  also  characteristic  of 
animals,  and  is,  at  least  in  part,  a  matter  of  inheritance. 


10. 

The  deviation  of  a  sensation  from  the  mean  of  the 
adjacent  sensations  is  always  noticeable,  and  exacts  a 
special  effort  on  the  part  of  the  sense-organ.  Every  new 
turn  of  a  curve,  every  projection  or  depression  of  a  surface, 
involves  a  deviation  of  some  space-sensation  from  the 
mean  of  the  surrounding  field  on  which  the  attention  is 


2i6        THE  ANALYSIS  OF  SENSATIONS 

directed.  The  plane  is  distinguished  physiologically  by 
the  fact  that  this  deviation  from  the  mean  is  a  minimum, 
or  for  each  point  in  particular  =  o.  In  looking  through  a 
stereoscope  at  a  spotted  surface,  the  separate  images  of 
which  have  not  yet  been  combined  into  a  binocular  image, 
we  experience  a  peculiarly  agreeable  impression  when  the 
whole  is  suddenly  flattened  out  into  a  plane.  The  aesthetic 
impressions  produced  by  the  circle  and  the  sphere  seem 
to  have  their  source  mainly  in  the  fact  that  the  above- 
mentioned  deviation  from  the  mean  is  the  same  for  all 
points. 

1 1. 

That  the  deviation  from  the  mean  of  the  environment 
plays  a  r61e  in  light-sensation  I  pointed  out  many  years 
ago.1  If  a  row  of  black  and  white  sectors,  such  as  are 
shown  in  Fig.  27,  be  painted  on  a  strip  of  paper  AABB^ 
and  this  be  then  wrapped  about  a  cylinder  the  axis  of 
which  is  parallel  to  AB,  there  will  be  produced,  on  the 
rapid  rotation  of  the  cylinder,  a  grey  field  with  increasing 
illumination  from  B  to  A,  in  which,  however,  a  brighter 
line  a  a,  and  a  darker  line  /3  /3,  make  their  appearance. 
The  points  which  correspond  to  the  indentations  a  are 
not  physically  brighter  than  the  neighboring  parts,  but 
their  light-intensity  exceeds  the  mean  intensity  of  the 
immediately  adjacent  parts,  while,  on  the  other  hand,  the 

1 "  Ueber  die  Wirkung  der  raumlichen  Vertheilung  des  Lichtreizes  auf 
die  Netzhaut,"  Sitzungsberichle  der  Wiener  Akademie  (1865),  Vol. 
LII.  Continuation  of  the  same  inquiry:  Sitzber.  (1866),  Vol.  LIV.  ; 
Sitzber.  (1868),  Vol.  LVII.  ;  Vierteljahrsschrift  fur  Psychiatrie, 
Neuwied- Leipzig,  1868  ("  Ueber  die  Abhangigkeit  der  Netzhautstellen 
von  einander  "). 


THE  ANALYSIS  OF  SENSATIONS        217 

light-intensity  at  /3  falls  short  of  the  mean  intensity  of  the 
adjacent  parts.1  This  deviation  from  the  mean  is  thus 
distinctly  felt,  and  accordingly  imposes  a  special  burden 
upon  the  organ  of  sight.  On  the  other  hand  a  continuous 
change  in  brightness  is  scarcely  noticed,  as  long  as  the 
brightness  of  each  particular  point  corresponds  to  the  mean 
of  the  adjacent  points.  Long  ago  I  drew  attention  to  the 
important  teleological  bearing  of  this  fact  on  the  saliency 
and  the  delimitation  of  objects  (Sitzungsberichte  der  Wiener 
Akademie  October  1865,  and  January  1868).  Small 
differences  are  slurred  over  by  the  retina,  and  larger 
A A 


Fig.  27. 

differences  stand  out  with  disproportionate  clearness. 
The  retina  schematizes  and  caricatures.  At  an  even 
earlier  period  the  important  part  which  outlines  play  in 
vision  had  been  noticed  by  Panum. 

A  series  of  very  various  experiments,  of  which  that  repre- 
sented in  Fig.  27  is  one  of  the  simplest,  led  me  to  the 
conclusion  that  the  illumination  of  a  position  on  the  retina 
is  felt  in  proportion  to  its  deviation  from  the  mean  of  the 

1  A  remark  concerning  the  analogies  between  light-sensation  and 
the  potential  function  will  be  found  in  my  note  "  Ueber  Herrn 
Gu6bhards  Darstellung  der  Aequipotentialkurven,"  Wiedemann's 
Annalen,  1882,  Vol.  XVII.,  p.  864;  and  see  my  Prinzipien  der 
Warmelehre,  2nd  edition,  1900,  p.  118. 


218        THE  ANALYSIS  OF  SENSATIONS 

illuminations  of  the  adjacent  positions.  The  value  of  the 
retinal  positions  in  determining  this  mean  is  to  be  conceived 
as  rapidly  decreasing  with  their  distance  from  the  position 
under  consideration,  a  fact  which  of  course  can  only  be 
explained  as  depending  on  an  organic  reciprocal  action  of 
the  retinal  elements  on  one  another.  Let  i=f  (x,  y)  be 
the  intensity  of  illumination  of  the  retina  with  reference  to 
a  system  of  co-ordinates  (XY);  then  the  mean  value  deter- 
mining the  intensity  for  a  given  position  may  be  symbolically 
represented  as  approximately 


where  m  is  constant,  and  the  radii  of  all  curves  of  the 
surface  /  (x,  y)  are  taken  as  large  in  proportion  to  the 
distance  at  which  the  retinal  positions  are  still  perceptibly 

influenced.     Now  according  as  f_I+_ljis  positive  or 

negative,  the  position  on  the  retina  experiences  a  darker  or 
a  brighter  sensation  respectively  than  it  does  under  equal 
illumination  of  the  adjacent  positions  with  the  intensity 
corresponding  to  itself.  If  the  surface  /  (x,  y)  has  edges 

and  indentations,   ( — a4-~T  ]  becomes  infinite,  and  the 
\  4&    <y2  / 

formula  is  useless.  In  this  case,  however,  a  marked  increase 
of  darkness  or  brightness  corresponds  to  the  indentation, 
though  of  course  not  an  infinite  increase  or  decrease.  The 
increase  or  decrease,  again,  are  not  denned  by  a  hard  and 
fast  line,  but  fade  gradually  away,  as  we  should  expect  from 
the  principle  of  deviation  from  the  mean.  For  the  retina 
consists,  not  of  sensitive  points,  but  of  an  infinite  number 
of  sensitive  elements  of  finite  extension.  As  regards  the 


THE  ANALYSIS  OF  SENSATIONS        219 

law  of  the  reciprocal  action  of  these  elements,  we  still  do 
not  know  it  accurately  enough  to  enable  us  to  determine 
precisely  the  phenomena  of  this  special  case. 

It  is  easy  to  go  wrong  in  judging  of  the  objective  distri- 
bution of  light  according  to  the  subjective  impression,  and 
consequently  a  knowledge  of  the  above-mentioned  law  of 
contrast  is  important  even  for  purely  physical  researches. 
Thus  Grimaldi  was  deceived  by  a  phenomenon  of  this  kind. 
We  come  across  the  same  phenomenon  in  the  investigation 
of  shadows,  and  of  spectral  absorption,  and  in  countless 
other  cases.  Peculiar  circumstances  prevented  my  papers  on 
this  subject  from  becoming  generally  known,  and  the  relevant 
facts  were  discovered  for  the  second  time  thirty  years  later.1 

It  may  seem  surprising  that,  in  addition  to  /,  the  second 

differential  quotients  of  *,  but  not  the  first,  — ,     — ,    seem 

dx      oy 

to  influence  the  sensation  of  brightness.  We  scarcely  notice 
a  regular  and  continuous  rise  in  the  intensity  of  illumination 
of  a  surface, — for  instance,  in  the  direction  xt — and  special 
devices  are  necessary  to  convince  one  that  there  is  a  rise. 
On  the  other  hand,  these  first  differential  quotients  exercise 
an  influence  on  the  modelling,  on  the  plastic  quality, 

1  H.  Seeliger,  "  Die  scheinbare  Vergrosserung  des  Erdschattens  bei 
Mondfinsternissen,"  Abhandlungen  der  Munchener  Akademie^  1896 ; 
H.  Haga  and  C.  H.  Wind,  "  Beugung  der  Rontgenstrahlen,"  Wiede- 
mann's  Annalen,  Vol.  LXVIII.,  1899,  p.  866;  C.  H.  Wind,  "Zur 
Demonstration  einer  von  E.  Mach  entdeckten  optischen  Tauschung," 
Riecke  and  Simon's  Physikalische  Zeitschrift^  I.,  No.  10.  A.  von 
Obermayer  ("  Ueber  die  Saumeum  die  Bilder  dunkler  Gegenstande  auf 
hellem  Hintergrunde,"  Eder's  Jahrbiich  der  Photographic ;  1900)  pub- 
lished a  number  of  new  facts  which  can  be  explained  on  the  law  of 
contrast  laid  down  in  the  text.  But,  of  my  four  papers,  he  is  only 
acquainted  with  the  first,  and  consequently  states  the  law  in  its  earlier 
defective  form. 


220        THE  ANALYSIS  OF  SENSATIONS 

of  the  surface  seen.  Call  the  horizontal  direction  x,  and 
the  distance  as  regards  depth  of  a  point  on  the  illuminated 

surface  r ;  then  —  and  — ^  are  parallel.    This  expression, 

which  of  course  is  only  to  be  understood  symbolically, 
means  that  we  have  the  representation  of  a  cylindrical 
surface  with  vertical  generatrix  and  plane  horizontal 
directrix  r  =  F  (jc),  of  which  the  second  differential 

<y2r 
quotients  — ^  (curvatures)  are  parallel  to  the  first  differential 

oOC 

quotients, — the  rises  in  intensity  of  illumination.  The 
tracing  of  the  curve  is  determined  by  the  accessory  circum- 
stances indicated  on  p.  210. 


12. 

With    regard    to    the    depth-sensations    excited    by    a 
monocular  image,  the  following  experiments  are  instructive. 
Fig.  28  is  a  plane  quadrilateral  with  its  two  diagonals.     If 
we  regard  it  monocularly,  it  is  most  easily 
seen,  according  to   the   laws  of  probability 
and   economy,  as   a   plane.      In   the  great 
majority    of  cases,   objects    which   are   not 
plane,  force  the  eye  to  the  vision  of  depth. 
^      .      -    Where  this  compulsion  is  lacking,  the  plane 
^^^       object  is  the  most  probable  and  at  the  same 
F»g.  28.         time  the  most  convenient  for  the  organ  of 

sight. 

The  same  drawing  may  be  also  viewed  monocularly  as  a 
tetrahedron,  the  edge  b  d  of  which  lies  in  front  of  a  c,  or  as 
a  tetrahedron,  the  edge  b  d  of  which  lies  behind  a  c.  The 


THE  ANALYSIS  OF  SENSATIONS        221 

influence  of  the  imagination  and  the  will  upon  the  visual 
process  is  extremely  limited ;  it  is  restricted  to  the  directing 
of  the  attention  and  to  the  selection  of  the  appropriate  dis- 
position of  the  organ  of  sight  for  one  of  a  number  of  cases 
given  by  habit,  of  which,  however,  each  one,  when  chosen, 
takes  its  place  with  mechanical  certainty  and  precision. 
Looking  at  the  point  ey  we  can,  as  a  fact,  produce  either  of 
the  two  optically  possible  tetrahedrons  at  will,  according  as  we 
represent  to  ourselves  b  d  as  nearer  or  farther  away  than  a  c. 
The  organ  of  sight  is  practised  in  the  representation  of  these 
two  cases,  since  it  often  happens  that  one  body  is  partly 
covered  by  another. 

Loeb I  thinks  that  the  act  of  bringing  Fig.  3 1  nearer  to 
the  eyes  gives  rise  to  short-distance  accommodation,  and 
thereby  also  to  our  seeing  the  fixed  edge  b  e  as  raised.  I 
have  not  been  able  to  obtain  any  such  definite  result  myself, 
nor  can  I  find  any  sufficient  theoretical  ground  for  it,2 
although  I  readily  admit  that  changes  in  the  distance  of  the 
figure  easily  lead  to  changes  in  our  view  of  it. 

The  same  figure  may,  finally,  be  seen  as  a  four-sided 
pyramid,  if  we  imagine  the  conspicuously  situated  point  of 
intersection  e  before  or  behind  the  plane  abed.  This  is 
difficult  to  do,  lib  e  d  and  a  e  c  are  two  perfectly  straight 
lines,  because  it  conflicts  with  the  habit  of  the  organ  of 
sight  to  see,  without  constraint,  a  straight  line  bent;  the 
effort  is  successful  only  because  the  point  e  has  a  con- 

1  Loeb,  "  Ueber  optische  Inversion,"  Pfliiger's  Archiv,  Vol.  XL., 
1887,  p.  247. 

2  Hillebrand  ("  Verhaltnis  von  Akkommodation   und   Konvergenz 
zur  Tiefenlokalisation,"  Zeitschrift  fur  Psychologic  und  Physiologic  der 
Sinnesorgane,  Vol.  VII.,  p,  97)  has  proved  the  slight  importance  which 
accommodation  has  for  the  seeing  of  depth. 


222         THE  ANALYSIS  OF  SENSATIONS 

spicuous  position.     But  if  there  is  a  slight  indentation  at  e, 
the  attempt  involves  no  difficulty. 

The  effect  of  a  linear  perspective  drawing  is  felt  as 
unerringly  by  one  who  is  ignorant  of  perspective  as  by 
one  who  is  thoroughly  conversant  with  the  theory,  provided 
he  is  able  to  disregard  the  plane  of  the  drawing, — a  con- 
dition readily  fulfilled  in  monocular  observation.  Reflexion, 
and  even  the  remembrance  of  seen  objects,  have,  according 
to  my  belief,  little  or  nothing  to  do  with  the  effect  in 
question.  Why  the  straight  lines  of  a  drawing  are  seen  as 
spatial  straight  lines,  has  already  been  pointed  out.  Where 
straight  lines  appear  to  converge  to  a  point 
in  the  plane  of  the  drawing,  the  converging 
or  approaching  ends  are  transferred,  accord- 
ing to  the  principles  of  probability  and 
economy,  to  like  or  to  nearly  like  depth. 
This  gives  us  the  effect  of  vanishing  points. 

Fig.  29. 

It  is  possible  to  see  such  lines  as  parallel, 
but  there  is  no  necessity  for  such  an  impression.  If  we 
hold  the  drawing,  Fig.  29,  on  a  level  with  the  eye,  it  may 
represent  to  us  a  glance  down  a  passage-way.  The  ends 
ghef are  transferred  to  like  distances.  If  the  distance 
is  great,  the  lines  ae^bf^cg^dh  appear  horizontal.  If  we 
raise  the  drawing,  the  ends  efgh  rise,  and  the  floor  abef 
seems  to  have  an  upward  slope.  Upon  lowering  the  draw- 
ing, the  opposite  phenomenon  is  presented ;  and  analogous 
changes  may  be  observed  by  moving  the  drawing  towards 
the  right  or  the  left.  In  these  facts,  the  elements  of  per- 
spective effect  find  simple  and  clear  expression. 

Plane  drawings,  provided  they  consist  entirely  of  straight 
lines,  everywhere  intersecting  each  other   at  right  angles, 


THE  ANALYSIS  OF  SENSATIONS        223 

almost  always  appear  plane.     If  oblique  intersections  and 

curved  lines  occur,  the  lines  easily  pass  out  of 

the  plane  ;  as  is  shown,  for  example,  by  Fig.  30^ 

which  may,  without  difficulty,  be  conceived  as 

a  curved  sheet  of  paper.     When  outlines,  such 

as  are  represented   in  Fig.  30,  have  assumed 

definite    spatial    form,   and    are    seen   as   the 

IR  30. 
boundary  of  a  surface,  the  latter,  to  describe 

it  briefly,  appears  as  flat  as  possible,  that  is  to  say,  is 
presented  with  a  minimum  of  deviation  from  the  mean 
of  the  depth-sensation.1 


The  peculiar  reciprocal  action  of  lines  intersecting 
obliquely  in  the  plane  of  the  drawing  (or  on  the  retina), 
whereby  such  lines  are  mutually  forced  out  of  the  plane  of 
the  drawing  (or  out  of  the  plane  perpendicular 
to  the  line  of  sight)  was  first  observed  by  me 
on  the  occasion  of  the  above-mentioned  (p.  209) 
experiment  with  the  monocular  inversion  of  a 
card.  The  card  in  Fig.  31,  whose  edge  b  e 
when  turned  outwards  towards  me  is  in  a 
vertical  position,  assumes,  when  I  succeed  in 
seeing  b  e  depressed,  a  recumbent  position,  like  that  of  a 
book  lying  open  upon  my  table,  with  the  result  that  b 
appears  further  away  than  e.  When  one  is  once  acquainted 
with  this  phenomenon,  the  inversion  may  be  performed 

1  Here  again,  the  depth-sensation  resembles  the  potential  function, 
in  a  space  at  the  boundaries  of  which  it  is  determined.  This  flat-as- 
possible  surface  does  not  coincide  with  the  surface  of  minimal  area, 
which  would  be  obtained  if  the  spatial  outlines  were  made  of  wire,  and 
then  dipped  in  soap-suds,  producing  a  Plateau's  liquid  film. 


224        THE  ANALYSIS  OF  SENSATIONS 


with  almost  every  object,  and  one  can  always  observe  along 
with  the  change  of  form  or  tilting  over,  this  remarkable 
simultaneous  change  of  position.  The  effect  is  especially 
astonishing  in  the  case  of  transparent  objects.  Let  abed 
be  a  section  of  a  glass  cube  lying  on  a  table  /  /,  and  let  O 
be  the  eye  (Fig.  32).  On  monocular  inversion,  the  angle 
a  is  projected  to  a1 ',  b  to  the  nearer  point  V ',  t  to  </,  and 
d  to  d'.  The  cube  will  seem  to  stand  obliquely  on  its  edge 
cf  upon  the  table  t'  /'.  In  order  that  the  drawing  might 

afford  a  better  survey  of  the 
phenomenon,  the  two  images 
have  been  represented  behind, 
not  within  one  another.  If  a 
drinking-glass  partly  filled  with 
a  colored  liquid  be  substi- 
tuted for  the  cube,  it  will  be 
seen,  together  with  the  surface 
of  the  liquid,  in  a  similar  oblique  position. 

With  sufficient  attention,  the  same  phenomena  may  be 
observed  with  any  linear  drawing.     If  we  place  the  page 
containing  Fig.  31   vertically  before  us,   and 
observe  it  monocularly,  we  shall  see  b  project 
if  b  e  be  raised,  but  if  b  e  be  depressed  b  will 
retreat  and  e  will  project  and  come  nearer  to 
the  observer.     Loeb  l  notices  that  when  this 
happens  the  points  a  e  remain  in  the  plane 
of  the  drawing.     And,  in  fact,  this  makes  the 
change  of  direction  intelligible.     If  we  draw 
the  dotted  lines,  as  in  Fig.  3  2  A,  and  imagine  the  figure, 
so  far  as  it  lies  outside  the  dotted  triangle,  obliterated,  we 
1  Loeb,  "  Ueber  optische  Inversion,"  quoted  p.  221  above. 


Fig    32 


THE  ANALYSIS  OF  SENSATIONS        225 

are  left  with  the  image  of  a  hollow  or  raised  three-sided 
pyramid,  which  lies  with  its  base  in  the  plane  of  the  draw- 
ing. Inversion  no  longer  produces  any  sort  of  mysterious 
change  of  position.  It  would  seem,  therefore,  that  every 
point  seen  monocularly  aims  at  the  minimum  deviation 
from  the  mean  of  the  sensation  of  depth,  which  is  attainable 
under  the  conditions  of  the  experiment,  and  that  the  whole 
object  seen  aims  at  the  minimum  attainable  amount  of 
removal  from  Hering's  nucleus-surface. 

When  we  consider  the  deformations  which  a  plane 
rectilinear  figure  undergoes  when  traced  in  monocular 
space,  all  such  deformations  may  be  qualitatively  reduced 
to  the  following  principle :  the  legs  of  an  acute  angle  are 
thrust  out  on  opposite  sides  of  the  plane  of  the  drawing,  or 
of  the  plane  perpendicular  to  the  line  of  sight,  and  the  legs 
of  an  obtuse  angle  are  thrust  out  on  the  same  side.  In 
this  process  acute  angles  are  magnified  and  obtuse  angles 
diminished.  All  angles  tend  to  become  right  angles. 

14. 

This  principle  suggests  that  the  phenomenon  just 
described  is  closely  related  to  Zollner's  pseudoscopy  and  the 
numerous  phenomena  connected  with  it.  Here  again 
everything  turns  on  the  apparent  enlargement  of  acute  and 
the  apparent  reduction  of  obtuse  angles,  except  that  the 
drawings  are  seen  in  the  plane.  But  when  they  are  seen  in 
monocular  space  the  pseudoscopic  effects  vanish,  and  the 
phenomena  described  above  appear.  Now  although  these 
phenomena  have  been  much  studied,  no  completely 
satisfactory  explanation  of  them  has  as  yet  been  offered. 
Naturally  such  superficial  explanations  as,  for  instance,  the 


226        THE  ANALYSIS  OF  SENSATIONS 

assumption  that  we  are  chiefly  accustomed  to  see  right 
angles,  are  inadmissible,  if  the  investigation  is  not  utterly  to 
miscarry  or  to  be  prematurely  broken  off.  We  see  oblique- 
angled  objects  often  enough,  but  never,  without  artificial 
preparation,  the  surface  of  a  liquid  at  rest  and  yet  oblique, 
as  we  did  in  the  experiment  given  above.  Yet,  the  eye,  it 
would  seem,  prefers  the  oblique  liquid  surface  to  an  oblique- 
angled  body. 

The  elemental  power  displayed  in  these  processes  has,  I 
believe,  its  root  in  far  simpler  habits  of  the  organ  of  sight, — 
habits  whose  origin  doubtless  antedates  the  civilized  life  of 
man.  I  once  tried  to  explain  the  phenomena  in  question 
by  a  contrast  of  directions  analogous  to  the  contrast  of 
colors,  but  without  arriving  at  a  satisfactory  result.  But 
more  recent  researches  by  Loeb,1  Heymans,2  and  others, 
and  observations  by  Hoefler 3  on  curve-contrasts,  are  very 
much  in  favor  of  a  theory  of  contrast.  Moreover,  quite 
lately  at  any  rate,  there  is  a  decidedly  increased  tendency  to 
adopt  some  purely  physiological  explanation. 4 

The  principle  of  economy,  again,  has  afforded  me  no 
enlightenment  as  far  as  Zollner's  pseudoscopy  is  concerned. 

A  somewhat  greater  prospect  of  success  seems  to  be 
offered  by  the  principle  of  probability.  Let  us  conceive 
the  retina  as  a  perfect  sphere  and  imagine  the  eye  fixed 
upon  the  vertex  of  an  angle  a  in  space.  The  planes  passing 
through  the  centre  of  the  eye  and  the  lines  containing  the 
angle,  project  these  lines  upon  the  retina,  describing  thereon 

1  Loeb,  Pfluger's  Archiv,  1895,  p.  509. 

2  Heyman's  Zcitschrift  fttr  Psychologic  und  Physiologic  dcr  Sinncs- 
organe,  Vol.  XIV.,  p.  101. 

3  Hoefler,  Ibid.,  Vol.  XII.,  p.  i. 

4  Witasek,  Ibid.,  Vol.  XIX,,  p.  I. 


THE  ANALYSIS  OF  SENSATIONS        227 

a  spherical  segment  having  the  angle  A,  which  represents  the 
angle  of  the  monocular  image.  Now  an  infinite  number  of 
values  for  a,  varying  from  o°  to  180°,  may  correspond 
to  a  constant  value  of  A,  as  will  be  seen  if  we  reflect  that 
the  lines  including  the  objective  angle  may  assume  every 
possible  position  in  the  planes  of  their  projection.  Conse- 
quently, to  a  seen  angle  A,  we  may  have  corresponding  all 
the  possible  values  of  the  objective  angle  a  that 
can  be  obtained  by  causing  each  of  the  sides,  b 
and  c,  of  the  triangle  to  vary  between  o°  and 
1  80°.  The  actual  result  is,  supposing  the  calcula- 
tion to  be  performed  in  a  definite  manner,  that 
larger  angles  are  the  most  probable  objects 
corresponding  to  observed  acute  angles,  and 
smaller  angles  the  most  likely  counterparts  of 
observed  obtuse  angles.  I  was  not,  however, 
in  a  position  to  determine  whether  those  cases, 
which  we  are  inclined  to  regard  as  geometrically  equally 
probable,  ought  also  to  be  regarded  as  physiologically 
equally  probable  —  a  question  which  is  both  essential 
and  important.  Moreover,  the  whole  conception  has  a 
much  too  artificial  cast  for  me. 


I  cannot  refrain  from  mentioning  here  the  attempt  which 
has  been  made  by  A.  Stohr  to  reach  an  explanation  of  the 
phenomena  described  above  from  an  entirely  new  point  of 
view.  With  the  general  considerations  by  which  he  was 
guided  I  am  in  full  sympathy  and  agreement.  On  the  other 
hand,  I  have  not  yet  been  able  to  convince  myself  that  there 
is  a  demonstrable  foundation  of  fact  corresponding  to  his 


228        THE  ANALYSIS  OF  SENSATIONS 

hypotheses.  Moreover,  the  relations  which  he  presupposes 
are  so  complicated  that  it  is  not  easy  to  decide  this  question, 
without  thoroughly  covering  the  ground  experimentally 
oneself.  I  therefore  do  not  know  whether  Stohr's  views 
will  amount  to  a  complete  explanation  on  all  points.  In 
one  of  his  less  recent  works *  the  assumption  is  made  that 
to  the  dioptric  image  of  the  eye  in  front  of  the  retina, 
there  corresponds  a  catoptric  image  in  the  retina,  the 
latter  having  relief  in  proportion  to  the  depth  of  the  former. 
Depth  in  the  retina  is  thus  both  the  determining  factor  for 
the  sensation  of  depth  in  visual  space,  and  the  regulating 
factor  in  accommodation.  As  a  matter  of  fact,  I  have  always 
asked  myself  what  the  means  could  be  by  which  the 
direction  of  change  of  accommodation  is  determined  ;  for 
change  of  accommodation  cannot  be  determined  merely  by 
the  magnitude  of  the  circle  of  dispersion ;  also  there  is  only 
a  loose  connection  between  accommodation  and  conver- 
gence, and  moreover  a  single  eye  by  itself  is  accommodated. 
Against  this  view,  on  the  other  hand,  must  be  set  the 
numerous  observations  which  have  been  made  as  to  the 
worthlessness  of  accommodation  for  the  sensation  of  depth. 
The  great  thickness  of  the  retina  in  the  eyes  of  insects  2 
suggests,  again,  that  the  perception  of  relief  may  be  con- 
nected with  some  function  of  the  retina. 

In  two  later  works 3  he  goes  further,  taking  this  theory  as 
a  basis.  In  the  second  of  these  books  we  find  a  view  not 
unlike  Scheffler's,  but  in  a  more  physiological  form.  The 

1  Zur  nativistiscken  Behandhmg  des  Tiefensehens,  Vienna,  1892. 
2Exner,  Die  physiologic  der  facettierten  Augen,  p.  188,  Vienna,  1891. 
3  Zur  Erklamng  der  Zollnerschen  Pseiidoskopie,  Vienna,  1898  ;  Bino- 
kulare  Figurmischimg  und  Pseudoskopie,  Vienna,  1900. 


THE  ANALYSIS  OF  SENSATIONS        229 

dominant  view,  according  to  which  the  images  of  positions 
which  deviate  more  or  less  from  the  corresponding  positions 
are  fused  into  one  unified  impression,  Stohr  thinks  is  unten- 
able. "Where  is  the  pointsman  who  arranges  the  change 
in  such  a  way  that,  not  only  in  extraordinary  cases,  but  also 
as  of  set  purpose,  two  stimuli  may  be  brought  into  com- 
bination in  the  central  organ  over  a  quite  unfamiliar  pair  of 
lines  of  conduction?"  It  is  assumed  that  the  retinae  of 
both  eyes  naturally  endeavour  to  minimalize  the  light- 
stimulus,  and  thus  tend  towards  the  equalization  of  unequal 
images.  The  nervous  elements  excite  the  ciliary  muscle, 
doing  this  not  only  in  a  quite  regular  and  uniform  manner, 
but  also,  according  to  requirements,  with  great  irregularity. 
Regular  contraction  of  the  ciliary  muscle  produces  a  greater 
bulging  of  the  lens  and  slight  contraction  of  the  retina.  If 
in  this  process  the  retinal  elements  carry  their  position-values 
with  them,  the  same  retinal  image  appears  enlarged.  In 
this  way,  according  to  Stohr,  we  can  understand  why 
Panum's  proportional  systems  of  circles  (up  to  circles  with 
radii  in  the  proportion  of  4  to  5)  are  seen,  in  virtue  of  the 
mutual  adaptation  of  the  two  eyes,  with  identical  parts  of 
the  retina,  as  simple  and  as  having  a  size  which  is  the  mean 
of  their  sizes.  By  depicting  one  system  in  red  and  the 
other  in  green  points  alternately,  so  that  in  the  united 
binocular  image  the  red  points  appear  between  the  green, 
Stohr  proves  that  the  fusion  of  the  systems  of  circles  is  not 
caused  by  the  suppression  of  one  of  the  images.  And 
irregular  contraction  of  the  ciliary  muscle  is  supposed  to 
produce  various  effects, — (i)  an  irregular  deformation  ot 
the  lens  with  very  various  displacements  of  the  apices  of 
the  diacaustic  of  different  pencils  of  rays,  whereby  change 


230        THE  ANALYSIS  OF  SENSATIONS 

in  the  relief  of  the  dioptric  and  catoptric  images  is  pro- 
duced ;  and  (2)  various  minimal  deformations  of  the  retina. 
Stohr  thinks  that  he  can  demonstrate  the  possibility  of  his 
theory  by  detailed  calculations,  and  that  he  can  prove  the 
actuality  of  his  presuppositions  by  investigating  subjects 
with  eyes  in  which  the  crystalline  lens  is  absent  or  out  of  its 
proper  position  (aphakia).  In  any  case  his  theory  has  led 
to  experiments  with  surprising  results, — for  instance,  the 
stereoscopic  indentation  of  straight  lines, — and,  if  only  on 
that  account,  it  deserves  to  be  considered  with  respect.  But 
although  his  whole  conception  of  the  eye  and  its  parts  as 
living  organisms  is  extremely  congenial  to  me,  I  have  not 
yet  been  able  to  convince  myself  that  the  assumptions 
which  he  makes  in  order  to  explain  more  complicated  cases 
of  spatial  vision  everywhere  fulfil  their  purpose.1 

Stohr's  departure  from  the  traditions  of  physiological 
optics  is  very  great.  In  itself  this  can  be  no  reason  for 
refusing  to  test  his  theory  closely,  especially  since  S.  Exner's 
and  Theodor  Beer's  2  researches  in  comparative  physiology, 
which  have  been  so  rich  in  beautiful  and  remarkable  results, 
have  made  us  familiar  with  eyes  characterized  by  a  com- 
plexity and  variety  of  organic  adaptation  such  as  a  physicist 
would  scarcely  have  supposed  possible  a  priori.  It  is 
possible  that  Stohr's  views  may  apply  to  other  organs  of 
vision,  although  perhaps  not  to  the  human  eye. 

1  The  following  book  has  subsequently  appeared  :  A.  Stohr,  Grund- 
fragen  der  psychc-physiologischen  Optik,  Leipzig  and  Vienna,  1904. 
The  problems  in  question  are  here  discussed  further. 

-  Th.  Beer,  "  Die  Akkommodation  des  Fischauges,"  Pfliiger's 
Archiv  Vol.  LVIIL,  p.  523  ;  "  Akkommodation  des  Auges  in  der 
Tierreihe,"  Wiener  klinische  Wochenschrift,  1808,  No.  XLII.  ; 
"  Ueber  primitive  Sehorgane,"  Ibid.,  1901,  Nos.  XL,  XII.,  XIII. 


THE  ANALYSIS  OF  SENSATIONS        231 

There  are  many  phenomena  that  make  it  probable  that 
the  act  of  sight  involves  other  processes  of  change  in  the 
eye  which  still  require  to  be  investigated.  Stereoscopic 
images  with  prominent  stereoscopic  differences  display, 
when  they  are  gazed  at  for  a  long  time,  an  enormous  increase 
in  the  growth  of  their  relief  by  successive  stages,  even 
though  fusion  has  apparently  been  complete  for  some  time. 
Wave-like  curvatures  and  swellings  have  been  observed  in 
systems  of  fine,  smooth,  parallel  lines,  and  these  have  been 
explained  in  a  rather  peculiar  manner  as  referable  to  the 
incapacity  of  the  mosaic-like  texture  of  the  retina  to  re- 
produce straight  lines  of  such  fineness.  I  have,  however, 
always  noticed  this  phenomenon  when  I  have  gazed  for 
some  time  at  systems  of  straight  lines  which  are  clearly 
visible  and  by  no  means  micrometric.  Thus  the  mosaic  of 
the  retina  can  have  nothing  to  do  with  the  matter.  I 
should  prefer  to  suppose  that  the  exertion  involved,  perhaps 
by  means  of  small  displacements  in  Stohr's  sense,  intro- 
duces a  certain  disorder  into  the  space-values.1 


16. 

The  ease  of  the  transition  from  the  process  of  seeing 
plane  figures  pseudoscopically  to  that  of  seeing  them 
monocularly  in  space  will  probably  help  us  to  throw  light 
upon  the  former.  This  conjecture  is  confirmed  by  the 
following  facts.  A  plane  linear  drawing,  monocularly  ob- 
served, usually  appears  plane.  But  if  the  angles  be  made 

1  "  Ueber  die  physiologische  Wirkung  raumlich  verteilter  Lichtreize," 
Wiener  Sitzungsberichte,  2nd  part,  October  1866,  pp.  7,  10,  of  the  off- 
print. 


232        THE  ANALYSIS  OF  SENSATIONS 

to  vary  and  motion  be  introduced,  every  drawing  of  this 
sort  will  assume  a  solid  form.  We  then  generally  see  a 
solid  body  in  rotation,  such  as  I  have  described  on  a  former 
occasion.1  The  well-known  vibrating  acoustic  figures  of 
Lissajous,  which  on  varying  their  difference  of  phase, 
appear  to  lie  on  a  revolving  cylinder,  afford  a  beautiful 
example  of  the  process  in  question. 

Here,  again,  reference  might  be  made  to  our  habit  of 
constantly  dealing  with  solid  bodies.  In  fact,  solid  bodies 
engaged  in  revolutions  and  turnings  continually  surround 
us.  Indeed,  the  whole  material  world  in  which  we  move 
is,  to  a  certain  extent,  a  single  solid  body ;  and  without 
the  help  of  solid  bodies  we  could  never  attain  to  the  con- 
ception of  geometrical  space.  We  do  not  generally  notice 
the  position  of  the  single  points  of  a  body  in  space,  but 
apprehend  its  dimensions  directly.  Herein  lies,  for  the 
unpractised,  the  main  difficulty  of  drawing  a  perspective 
picture.  Children,  who  are  accustomed  to  seeing  bodies 
in  their  real  dimensions,  do  not  understand  perspective 
foreshortenings,  and  are  far  better  satisfied  with  simple 
outlines  or  silhouettes.  I  can  well  remember  this  condition 
of  mind,  and  through  this  remembrance  am  able  to  com- 
prehend the  drawings  of  the  ancient  Egyptians,  which 
represent  all  parts  of  the  body  as  far  as  possible  in  their 
true  dimensions,  thus  pressing  them,  as  it  were,  into  the 
plane  of  the  drawing,  as  plants  are  pressed  in  a  herbarium. 
In  the  Pompeian  wall-paintings,  too,  we  still  meet  with 
a  perceptible  dislike  for  foreshortening,  although  here 
the  sense  of  perspective  is  already  manifest.  The  old 

1  "  Beobachtungen  iiber  monokulare  Stereoskopie,"  Sitzungsberichte 
der  Wiener  A kademie  (1868),  Vol.  LVIII. 


THE  ANALYSIS  OF  SENSATIONS        233 

Italian  masters,  on  the  other  hand,  in  the  consciousness  of 
their  perfect  mastery  of  the  subject,  often  amuse  themselves 
with  excessive  and  sometimes  even  unbeautiful  foreshorten- 
ings,  which  occasionally  demand  considerable  exertion  of 
the  eye. 


There  can  be  no  question,  therefore,  but  that  we  are 
much  more  familiar  with  the  process  of  seeing  solid  bodies 
with  the  distances  between  their  salient  points  unchanged, 
than  with  the  process  of  separating  out  their  depth,  which 
is  always  the  result,  in  the  first  place,  of  deliberate  analysis. 
Accordingly,  we  may  expect  that  wherever  a  coherent  mass 
of  sensations,  which,  in  virtue  of  its  continuous  transitions 
and  its  common  coloring,  merged  into  a  unity,  exhibits 
spatial  alteration,  the  change  will  be  seen  preferably  as  the 
motion  of  a  solid  body.  I  must  confess,  however,  that  this 
way  of  looking  at  the  matter  does  not  satisfy  me.  I  believe, 
rather,  that  here,  too,  an  elementary  habit  of  the  organ  of 
sight  is  at  the  root  of  the  matter,  —  a  habit  which  did  not 
originally  arise  through  the  conscious  experience  of  the 
individual,  but,  on  the  contrary,  antecedently  facilitated 
our  apprehension  of  the  movements  of  solid  bodies.  If 
we  should  assume,  for  example,  that  every  diminution  of 
the  transverse  dimension  of  an  optical  sensation-mass  to 
which  the  attention  was  directed  had  the  tendency  to  induce 
a  corresponding  augmentation  of  the  dimension  of  depth, 
and  vice  versa,  we  should  have  a  process  quite  analogous 
to  that  which  we  have  already  considered  above  (p.  199) 
and  which  was  compared  with  the  conservation  of  energy. 
This  view  is  certainly  much  simpler  and  supplies  an  equally 


234        THE  ANALYSIS  OF  SENSATIONS 

adequate  explanation.  Furthermore,  it  enables  us  to 
comprehend  more  easily  how  such  an  elementary  habit 
could  be  acquired,  how  it  could  find  expression  in  the 
organism,  and  how  the  disposition  towards  it  could  be 
inherited. 

As  a  sort  of  counterpart  to  the  rotation  of  solid  bodies 
exhibited  to  us  by  the  organ  of  sight,  I  will  cite  here  an 
additional  observation.  If  an  egg,  or  ellipsoid  with  dull, 
uniform  surface  be  rolled  over  the  top  of  a  table,  but  in 
such  manner  that  it  does  not  turn  about  its  axis  of  genera- 
tion, but  performs  jolting  movements,  we  shall  fancy 
we  see,  on  viewing  it  binocularly,  a  liquid  body,  or  large 
oscillating  drop.  The  phenomenon  is  still  more  noticeable 
if  the  egg,  with  its  longitudinal  axis  in  a  horizontal  position, 
be  set  in  moderately  rapid  rotation  about  a  vertical  axis. 
This  effect  is  immediately  destroyed  when  marks,  whose 
movements  we  may  follow,  are  made  upon  the  surface  of 
the  egg.  A  rotating  solid  body  is  then  seen. 

The  explanations  offered  in  this  chapter  are  certainly 
far  from  complete,  yet  I  believe  that  the  considerations 
adduced  will  have  some  effect  in  stimulating  and  preparing 
the  way  for  a  more  exact  and  thorough  study  of  these 
phenomena. 


XI.  SENSATION,    MEMORY   AND 
ASSOCIATION. 

I. 

THE  foregoing  discussions  have  shewn  beyond  all 
possible  doubt  that  out  of  mere  sensations  no 
psychical  life  resembling  ours  even  in  the  remotest  degree 
could  be  constituted.  When  a  sensation  is  forgotten  the 
moment  after  it  has  vanished,  the  only  possible  result  is  a 
disconnected  mosaic  and  series  of  psychic  states,  such  as 
we  have  to  suppose  in  the  case  of  the  lowest  animals  and 
the  most  degraded  idiots.  At  this  stage,  a  sensation  which 
does  not  have  some  such  effect  as  to  stimulate  violently 
to  movement — a  sensation  of  pain,  for  instance — will 
scarcely  receive  attention.  For  instance,  the  sight  of  a 
vividly-colored  spherical  body,  which  is  not  supplemented 
by  a  memory  of  smell  and  taste, — by  memory,  in  a  word, 
of  the  properties  of  a  fruit  and  the  experiences  connected 
with  a  fruit, — remains  unintelligible  and  is  devoid  of  interest, 
in  the  manner  that  has  been  observed  in  "  psychic  blind- 
ness." The  storing  up  and  connexion  of  memories,  and 
their  power  to  evoke  one  another, — in  short,  Memory 
and  Association, — are  the  fundamental  requirements  of  a 
developed  psychical  life. 

What  is  memory?  A  psychical  event  leaves  psychical 
traces  behind  it,  but  it  also  leaves  physical  traces.  Physi- 
cally, as  well  as  psychically,  a  child  that  has  been  burnt,  or 

235 


236        THE  ANALYSIS  OF  SENSATIONS 

stung  by  a  wasp,  behaves  in  quite  a  different  way  from  a 
child  that  has  not  had  this  experience.  For  the  psychical 
and  the  physical  are  different  only  according  to  the  way 
in  which  they  are  regarded.  Nevertheless  it  is  extremely 
difficult  to  discover  in  the  physical  phenomena  of  the 
inorganic  world  characteristics  having  any  affinity  to  memory. 

In  the  physics  of  the  inorganic  world  everything  seems 
to  be  determined  by  the  circumstances  of  the  moment,  and 
the  past  seems  to  be  entirely  without  any  influence.  The 
oscillations  of  a  pendulum  are  equal,  whether  it  is  perform- 
ing its  first  oscillation  or  whether  1000  others  have  already 
taken  place.  Hydrogen  combines  with  chlorine  in  the 
same  way,  no  matter  whether  it  was  previously  in  combina- 
tion with  bromine  or  with  iodine.  There  are  indeed,  even 
in  the  physical  sphere,  cases  in  which  the  influence  of  the 
past  is  clearly  expressed.  The  earth  reveals  to  us  the 
history  of  its  geological  past,  and  the  moon  does  the  same. 
My  friend  E.  Suess  has  shewn  me  a  piece  of  rock  marked 
with  a  system  of  very  peculiar  congruent  parallel  fissures, 
which  he  very  plausibly  interprets  as  a  prehistoric  seismogram. 

A  wire  notices,  so  to  speak,  during  a  considerable  time, 
every  torsion  that  it  sustains.  Every  spark  of  a  discharge 
is  an  individual,  and  is  influenced  by  the  discharges  that 
have  preceded  it.  The  insulating  layer  of  the  Leyden  jar 
preserves  a  history  of  all  the  previous  charges. 

The  apparent  contradiction  is  solved  when  we  remember 
how  in  physics  we  are  accustomed  to  idealize  and 
schematize  in  an  extreme  degree  the  cases  under  considera- 
tion, always  presupposing  the  simplest  possible  circum- 
stances. If  we  assume  a  mathematical  pendulum,  then  no 
doubt  the  thousandth  oscillation  is  as  the  first,  and  no 


THE  ANALYSIS  OF  SENSATIONS        237 

traces  of  the  past  are  visible,  precisely  because  we  disregard 
such  traces.  But  a  real  pendulum  wears  away  -its  knife- 
edge,  and  is  heated  by  internal  and  external  friction,  so  that 
no  oscillation,  accurately  considered,  is  exactly  like  any 
other.  The  result  of  every  second  and  third  torsion  of  a 
wire  is  somewhat  different  from  what  it  would  have  been 
if  there  had  been  no  previous  torsions.  If  a  similar 
schematization  were  possible  in  psychology,  we  should  have 
men  who  behave  identically  and  do  not  betray  any  of  the 
influence  of  individual  experiences. 

In  reality  every  psychical  process  leaves  indelible  traces 
behind,  just  as  every  physical  process  does.  In  both 
spheres  there  are  irreversible  processes  :  entropy  increases, 
or  the  bond  of  a  friendship  that  has  been  broken,  and  then 
renewed,  is  felt.  And  every  real  process  contains  at  any 
rate  some  irreversible  components. 


Now  it  will  be  said,  and  with  justice,  that  traces  of  the 
past  are  still  far  from  being  the  same  thing  as  memory. 
As  a  matter  of  fact,  what  is  required  to  increase  the 
resemblance  is,  that  processes  which  have  taken  place  in 
the  past  should  be  set  up  afresh  by  some  slight  impulse. 
Old  violins  that  have  been  well  played  on,  Moser's 
electrical  images  (that  come  out  when  breathed  upon), 
and  the  phonograph,  afford  rather  better  examples.  Still, 
violins  and  phonographs  have  to  be  played  by  external 
forces,  while  human  beings  and  their  memories  play  them- 
selves. For  organic  beings  are  not  rigid  material  systems ; 
they  are  essentially  forms  of  the  dynamic  equilibrium  of 


238        THE  ANALYSIS  OF  SENSATIONS 

currents  of  "matter"  and  "energy."  Now  it  is  the  forms 
of  the  deviation  of  these  currents  from  the  state  of  dynamic 
equilibrium  that  always  repeat  themselves  in  the  same  way, 
according  to  the  way  in  which  they  have  once  been  intro- 
duced. Such  variations  in  the  forms  of  dynamic  equilibrium 
have  still  been  but  little  studied  by  inorganic  physics.  As 
a  very  rough  example  we  may  take  changes  in  the  flow  of 
liquids,  produced  by  some  chance  circumstance,  and  then 
maintained.  If  we  screw  up  a  tap  so  tightly  that  only  a 
thin,  quiet  trickle  of  water  comes  but,  a  chance  jolt  is 
enough  to  disturb  the  unstable  equilibrium  of  the  trickle, 
and  to  cause  the  water  to  run  out  in  drops  with  a  persistent 
rhythm.  Suppose  that  a  chain,  lying  coiled  up  in  a  tub, 
is  allowed  to  run  over  a  roller  acting  as  a  sort  of  lever, 
and  to  fall  into  another  tub  at  a  lower  level.  If  the  chain 
is  very  long  and  the  difference  of  level  very  great,  the 
velocity  may.  become  considerable,  and  then  the  chain, 
as  is  well  known,  has  the  property,  whenever  it  is  made  to 
take  a  loop,  of  keeping  this  loop  suspended  in  the  air  for 
some  time,  and  continuing  its  flow  in  this  shape.  All  these 
examples  are  very  inadequate  analogies  to  the  plasticity 
which  organisms  possess  for  the  repetition  of  processes 
and  series  of  processes. 

The  foregoing  considerations  are  intended  to  shew  that 
a  comprehension  of  memory  on  physical  lines  is  not  un- 
attainable, although  we  are  still  very  far  removed  from  it. 
There  can  be  no  doubt  that  a  considerable  enlargement 
of  the  point  of  view  of  physical  science  by  means  of  the 
study  of  organic  beings  is  required,  before  physics  is 
capable  of  such  a  task.  The  great  richness  of  memory  is 
founded,  no  doubt,  upon  the  reciprocal  interaction  and 


THE  ANALYSIS  OF  SENSATIONS        239 

connexion  of  the  organs.  Still,  we  probably  must  ascribe 
a  rudimentary  memory  even  to  elementary  organisms ;  and 
if  so,  the  idea  inevitably  suggests  itself  that,  every  chemical 
process  in  the  organ  leaves  traces  behind  which  are  favour- 
able to  the  reappearance  of  the  same  process.1 


It  is  well  known  that  a  very  prominent  position  is  given, 
in  psychology,  to  the  laws  of  association.  These  laws  can 
be  reduced  to  a  single  law,  which  consists  in  saying  that  if 
two  contents  of  consciousness,  A  and  B,  have  once  appeared 
simultaneously,  one  of  them,  when  it  arises,  will  evoke  the 
other.  And  in  fact  it  is  much  easier  to  understand  physical 
life  when  we  have  recognized  the  constant  recurrence  of 
this  fundamental  feature.  The  differences  of  mental  pro- 
cess, in  simple  memory  of  an  experience,  in  serious  occupa- 
tion, and  in  the  free  exercise  of  fancy  or  day-dreaming,  can 
easily  be  understood  by  means  of  the  concomitant  cir- 
cumstances.2 It  would,  however,  be  a  complete  mistake  to 
try  to  reduce  <z//(p.  201)  psychical  processes  to  associations 
acquired  during  the  life  of  the  individual.  In  none  of  its 
phases  do  we  meet  with  the  psyche  as  a  tabula  rasa.  At 
the  very  least  we  should  have  to  assume  innate  associations 
side  by  side  with  the  acquired.  The  innate  impulses,3 

1  Ostwald  has  made  a  bold  attempt  at  a  chemical  theory  of  memory, 
based   on   his   theories  about  katalysis.       See   his    Vorlesimgen   fiber 
Naturphilosophie,  1902,  pp.  369  sqq. 

2  Mach,  Erkenntnis  und  Irrtuni,  1905,  pp.  29  sqq. 

3  The  most  striking  of  these,  because  they  make  their  appearance  at 
the  moment  when  the  mental  faculties  and  the  power  of  observation  are 
fully  developed,  are  the  first  manifestations  of  the  sexual  impulse.     I 


240        THE  ANALYSIS  OF  SENSATIONS 

which,  to  a  psychology  that  is  purely  introspective  and  con- 
fined to  itself,  must  necessarily  appear  to  be  innate  associa- 
tions, are  reduced  by  biology  to  innate  organic  connexions, 
and,  in  particular,  to  nervous  connexions.  It  is  therefore 
worth  while  to  inquire  whether  all  associations,  including 
those  acquired  by  the  individual,  do  not  depend  upon 
innate  connexions,  of  which  some  have  been  strengthened 
by  use.1  But  in  any  case  we  must  also  ask  whether  the 
processes  for  the  connexion  of  which  in  highly  different- 
iated organisms  special  paths  have  been  evolved,  are  not 
rather  primary  facts  that  already  exist  in  lower  organisms, 
and  whether  it  is  not  their  repeated  occurrence  accompanied 
by  one  another  that  has  led  to  the  formation  of  the  paths 
in  question.2  A  rational  psychology  cannot,  of  course,  be 
content  with  temporary  associations ;  it  will  have  to  provide 
for  fixed  paths  of  connexion  also.  Again,  room  must  be 
found  for  the  possibility  of  spontaneous  psychical  pro- 
cesses, not  due  to  association,  which  excite  the  neighbor- 
ing parts  of  the  nervous  system,  and,  when  they  are  of  great 

have  been  told  by  a  perfectly  trustworthy  man,  a  person  with  a  strong 
love  of  truth,  that  when  he  was  a  lad  of  sixteen,  being  quite  innocent 
and  inexperienced  at  the  time,  he  saw  a  lady  in  a  low-necked  dress, 
and  was  startled  to  find  that  he  was  suddenly  aware  of  a  striking  bodily 
change  in  his  person  ;  this  change  he  took  to  be  an  illness,  and  con- 
sulted a  colleague  about  it.  The  whole  complex  of  entirely  new 
sensations  and  feelings  which  were  then  suddenly  revealed  to  him  was 
colored  by  a  strong  additional  element  of  fear. 

1  H.  E.  Ziegler,  "  Theoretisches  zur  Tierphysiologie  und  vergleich- 
enden    Neurophysiologie,"   Biologisches  Zentralblatt ',    Leipzig,    1900, 
Vol.  XX  ,  No.   i. 

2  If  we  think  of  organic  life  as  a  state  of  dynamic  equilibrium  of 
various  chemical  component-phases,  in  which,  speaking  generally,  a 
disturbance  of  one  component  causes  a  disturbance  of  the  rest,  we  shall 
then  be  justified  in  hoping  to  explain,  not  only  memory,  but  association 
too,  on  chemical  lines.     See  p.  239  above,  note  i,  and  p.  99. 


THE  ANALYSIS  OF  SENSATIONS        241 

violence,  even  spread  over  the  whole  nervous  system.  On 
the  one  hand  hallucinations,  on  the  other  reflex  movements, 
are  examples  from  the  sensational  and  motor  spheres,  to 
which  there  are  probably  corresponding  analogies  in  other 
spheres. 


Theories  of  the  reciprocal  action  of  the  parts  of  the 
central  nervous  system  seem  to  be  opposed  to  a  view  which 
has  been  expounded  by  Loeb,1  partly  on  the  basis  of  his 
own  work,  partly  on  that  of  Goltz  and  Ewald.  This  view 
deserves  to  be  noticed.  According  to  it,  the  tropisms  of 
animals  are  not  essentially  different  from  those  of  plants, 
the  only  advantage  secured  by  the  nerves  in  the  case  of 
animals  being  the  more  rapid  transference  of  stimulus. 
The  life  of  the  nervous  system  is  reduced  to  segmental 
reflexes,  the  co-ordination  of  movements  to  reciprocal 
excitation  and  transference  of  stimulus,  and  the  instincts 
to  chains  of  reflexes.  The  snapping-reflex  of  the  frog,  for 
instance,  sets  free  the  swallo wing-reflex.  Organized  centres 
of  great  complication  are  not  assumed,  but  the  brain  itself 
is  regarded  as  an  arrangement  of  segments.  At  the  bottom 
of  all  these  theories  there  lies,  so  far  as  I  can  judge,  a 
happily  conceived  and  important  effort  to  shake  off  the 
trammels  of  unnecessarily  complicated  assumptions  impreg- 
nated with  metaphysics.  But  I  cannot  agree  with  Loeb 
when  he  treats  Darwin's  phylogenetic  research  on  the 
instincts  as  a  fallacious  and  one-sided  proceeding,  which 
ought  to  be  dropped  and  replaced  by  physico-chemical 
investigations.  Research  of  that  kind  was,  no  doubt,  not 
1  Loeb,  Vergleichende  Physiologic  des  Gehirns,  Leipzig,  1899. 
9 


242        THE  ANALYSIS  OF  SENSATIONS 

within  Darwin's  horizon.  But  it  was  precisely  that  fact 
which  secured  for  him  the  freedom  of  vision  necessary  to 
his  great  and  peculiar  discoveries,  which  no  physicist,  qua 
physicist,  could  have  made.  We  are,  indeed,  everywhere 
trying  to  obtain,  where  it  is  possible,  some  insight  into  the 
physical  constitution  of  things,  some  acquaintance  with 
their  immediate,  or  causal,  connexions.  But  it  is  far  from 
being  the  case  that  this  is  already  possible  everywhere. 
And  in  cases  where  it  is  not  possible,  it  would  at  all  events 
only  be  another  and  a  very  dangerous  piece  of  one-sidedness, 
to  give  up  other  fruitful  points  of  view,  which  can  always  be 
regarded  as  provisional.  The  steam-engine  can,  as  Loeb 
says,  only  be  understood  on  physical  lines.  But  this  is  only 
true  of  a  particular  given  steam-engine.  When  it  is  a 
question  of  understanding  the  present  forms  of  the  steam- 
engine,  physical  considerations  are  not  sufficient.  The 
whole  history  of  technical  and  social  culture,  and  the 
geological  presuppositions  involved,  must  be  taken  into 
account.  It  is  possible  that,  in  the  last  resort,  each  one  of 
these  factors  is  susceptible  of  a  physical  explanation,  but  it 
has  explained  our  difficulties  long  before  that  stage  is 
reached.1 

6. 

If  I  can  imagine  that,  while  I  am  having  sensations,  I 
myself  or  someone  else  could  observe  my  brain  with  all  the 
necessary  physical  and  chemical  appliances,  it  would  then 
be  possible  to  ascertain  with  what  processes  of  the  organism 
sensations  of  a  particular  kind  are  connected.  The  question 
so  often  asked,  what  is  the  lower  limit  of  sensation  in  the 
1  Loeb,  Vergleichende  Physiologic  des  Gehirns,  p.  1 30. 


THE  ANALYSIS  OF  SENSATIONS        243 

organic  world,  whether  the  lowest  animals  have  sensations, 
or  whether  plants  have,  could  then  be  brought  nearer  to  its 
solution,  at  any  rate  so  far  as  analogy  goes.  As  long  as 
this  problem  has  not  been  solved  in  even  one  single  special 
case,  no  decision  of  the  question  is  possible.  It  is  some- 
times even  asked  whether  inorganic  "matter"  has  sensa- 
tions. The  question  is  natural  enough,  if  we  start  from  the 
commonly  current  physical  conception  which  represents 
matter  as  the  immediately  and  undoubtedly  given  reality 
out  of  which  everything,  inorganic  and  organic,  is  con- 
structed ;  for  sensation  must  either  arise  suddenly  some- 
where or  other  in  this  structure,  or  else  have  been  present 
in  the  foundation-stones  from  the  beginning.  From  our 
point  of  view  the  question  is  merely  a  perversion.  Matter 
is  for  us  not  what  is  primarily  given.  What  is  primarily 
given  is,  rather,  the  elements,  which,  when  standing  to  one 
another  in  a  certain  known  relation,  are  called  sensations. 
Every  scientific  problem  that  can  have  any  meaning  for  a 
human  individual  is  concerned  with  the  ascertainment  of 
the  dependence  of  the  elements  on  one  another.  What  in 
every-day  life  we  call  matter  is  a  definite  kind  of  connexion 
between  the  elements.  The  question  as  to  whether  matter 
has  sensations  would  therefore  run  as  follows  :  does  sensa- 
tion belong  to  a  definite  kind  of  connexion  between  the 
elements,  these  elements  themselves  also  being,  when  in  a 
certain  relation,  always  sensations  ?  Put  in  this  form;  no 
one  will  want  to  ask  the  question.1  Everything  that  can 
have  any  interest  for  us  must  be  reached  in  the  course  of 
following  out  the  general  task  of  science.  We  ask  whether 

1  Cf.    Mach,  Popular-  Wissenschajtliche  Vorlesungen,  3rd  ed.,  1903, 
p.  242. 


244        THE  ANALYSIS  OF  SENSATIONS 

animals  have  sensations,  when  the  assumption  of  sensations 
helps  us  better  to  understand  their  behaviour  as  observed 
by  means  of  our  own  senses.  The  behaviour  of  a  crystal  is 
already  completely  determined  for  our  senses ;  and  thus  to 
ask  whether  a  crystal  has  sensations,  which  would  provide 
us  with  no  further  explanation  of  its  behaviour,  is  a 
question  without  any  practical  or  scientific  meaning. 


XII.  THE  SENSATION  OF  TIME.1 


i. 


MUCH  more  difficult  than  the  investigation  of 
space-sensation  is  that  of  time-sensation.  Many 
sensations  make  their  appearance  with,  others  without, 
a  clear  sensation  of  space.  But  time-sensation  accom- 
panies every  other  sensation,  and  can  be  wholly 
separated  from  none.  We  are  referred,  therefore,  in  our 
investigations  here,  to  the  variations  of  time-sensation. 
With  this  psychological  difficulty  is  associated  another, 
consisting  of  the  fact  that  the  physiological  processes  with 
which  the  sensation  of  time  is  connected  are  still  less 
known,  lie  deeper,  and  are  more  thoroughly  concealed 
than  the  processes  corresponding  to  the  other  sensations. 
Our  analysis,  therefore,  must  confine  itself  chiefly  to  the 
psychological  side,  without  approaching  the  question  from 
its  physical  aspect,  as  is  possible,  in  part  at  least,  in  the 
provinces  of  the  other  senses. 

It  is  scarcely  necessary  to  lay  special  emphasis  on  the 
important  part  played  in  our  psychical  life  by  the  temporal 

1  The  position  which  I  here  take  differs  only  slightly  from  that  of  my 
"  Untersuchungen  iiber  den  Zeitsinn  des  Ohres,"  Sitzber.  d.  Wiener 
Akademie,  Vol.  LI. ,  1865.  Into  the  details  of  these  earlier  experiments, 
begun  in  1860,  I  shall  not  enter  again  here.  Nor  can  I  here  discuss 
the  plentiful  material  which  has  resulted  from  the  works  of  Meumann, 
Munsterberg,  Schumann,  Nichols,  Hermann,  and  others.  Cp.  Scripture, 
The  New  Psychology,  London,  1897,  p.  170.  For  a  supplementary  dis- 
cussion, see  my  Erkenntnis  und  Irrtttm,  1905,  pp.  415  sqq. 

245 


246        THE  ANALYSIS  OF  SENSATIONS 

ordering  of  the  elements.  The  temporal  order  is  even 
more  important  than  the  spatial.  Reversal  of  the  temporal 
order  is  even  more  destructive  of  a  process  than  is  the 
reversal  of  an  object  in  space  by  turning  it  upside  down ; 
reverse  the  temporal  order,  and  an  experience  becomes 
something  other  than  itself,  something  quite  new.  This  is 
why  the  words  of  a  speech  or  a  poem  are  reproduced  only 
in  the  order  in  which  they  were  experienced  and  not  in  the 
reverse  order  as  well,  in  which  they  would  generally  have 
a  quite  different  meaning,  or  no  meaning  at  all.  If  the 
whole  acoustic  sequence  is  reversed  by  saying  something 
backwards,  or  by  making  a  phonograph  work  backwards, 
we  do  not  even  recognize  any  longer  the  words  that  are  the 
component  parts  of  the  speech.  Definite  memories  are  con- 
nected only  with  the  definite  sequence  of  sounds  in  which 
a  word  occurs,  and  it  is  only  when  the  memories  are 
evoked  in  a  definite  order  corresponding  to  the  word- 
sequence,  that  they  combine  together  to  produce  a  definite 
meaning.1  But  a  sequence  of  notes  too,  a  simple  melody 
in  which  habit  and  association  in  any  case  play  a  very 
small  part,  becomes  unrecognizable  if  it  is  temporally 
reversed.  As  regards  even  very  elementary  representa- 
tions and  sensations,  their  temporal  sequence  forms  part 
of  the  memory  image  of  them. 

If  we  conceive  time  as  a  sensation,  it  seems  less  strange 
that,  in  a  series  passing  in  the  order  A  B  CD  E,  any  member, 
C  for  instance,  should  call  up  to  the  memory  only  the 
members  that  follow  it,  and  not  those  that  precede.  The 

JCp.  R.  Wallaschek,  Psychologic  nnd  Pathologic  der  Vorstellung, 
Leipzig,  1905,  especially  the  chapter  on  "  The  Whole  and  its  Parts/' 
pp.  I5sqq. 


THE  ANALYSIS  OF  SENSATIONS        247 

memory-image  of  a  building  does  not  arise  with  the  roof 
turned  downwards.  But,  for  the  rest,  it  does  not  seem  to 
be  a  matter  of  indifference  whether  the  organ  B  is  excited 
after  an  organ  A,  or  vice  versa.  There  is  probably  a 
physiological  problem  concealed  here,  which  would  re- 
quire to  be  solved  before  we  can  fully  understand  the 
fundamental  psychological  fact  of  the  lapse  of  reproduced 
series  in  one  determined  direction.1  It  is  possible  that 
this  fact  is  connected  with  the  fact  that  an  excitation 
propagates  itself  along  entirely  different  paths  according 
to  the  point  at  which  it  first  enters  into  the  organism,  in 
the  way  in  which  this  was  explained  for  physical  cases  by 
the  considerations  on  p.  92  and  by  Fig.  \b.  Even  when 
the  medium  is  perfectly  homogeneous,  if  two  excitations 
in  it,  starting  from  two  distant  points,  spread  uniformly, 
they  will  more  nearly  coincide  at  that  one  of  the  two  points 
which  was  excited  later.  Thus,  even  in  the  simplest  cases, 
the  order  of  stimulation  cannot  be  a  matter  of  indifference. 
Let  a  note  D  follow  a  note  C.  The  impression  is  quite 
different  from  what  it  would  be  if  C  followed  D.  The 
cause  of  this  is  chiefly  the  notes  themselves,  and  their 
reciprocal  action.  For  if  the  pause  between  the  two  notes 
is  made  sufficiently  long,  it  is  possible  that  we  shall  no 
longer  distinguish  the  two  cases.  Something  analogous 
can  be  observed  with  sequences  of  colors,  and  in  general 

1  Perhaps  the  nervous  elements  are  not  merely  endowed  with  a  per- 
manent innate  faculty  of  polar  orientation,  such  as  is  made  probable  by 
the  backward  direction  of  the  wave  in  the  intestines  and  the  musculature 
of  snakes,  and  by  galvanotropic  phenomena,  but  perhaps  they  are  also 
capable  of  a  temporarily  acquired  polarity,  as  manifested  in  the 
inclusion  of  the  time-series  in  memory,  in  practice,  etc.  Cp.  Loeb  and 
Maxwell,  Zur  Theorie  des  Galvanotropismus^  Pfliiger's  Archiv,  Vol. 
LXIII.  p.  121 ;  Loeb,  Vergleichende.  Gehirnphysiologie,  pp.  108  sqq. 


248        THE  ANALYSIS  OF  SENSATIONS 

with  sensations  of  any  kind.  But  if  a  note  A  is  followed 
by  a  color  or  a  smell  B,  we  always  know  that  B  has  followed 
A,  and  our  estimate  of  the  pause  between  A  and  B  is 
practically  not  influenced  at  all  by  the  quality  of  A  and  B. 
There  must  therefore  be  a  further  process,  which  is  un- 
affected by  variation  in  the  quality  of  sensation,  which  is 
quite  independent  of  the  quality  of  sensation,  and  by 
means  of  which  we  estimate  time.  It  is  possible,  indeed, 
to  make  a  sort  of  rhythm  out  of  entirely  heterogeneous 
sensations,  such  as  sounds,  colors  and  impressions  of 
touch. 


That  a  definite,  specific  time-sensation  exists,  appears  to 
me  beyond  all  doubt.     The  rhythmical  identity  of  the  two 


r 

adjoined  measures,  in  which  the  sequence  of  the  notes  is 
quite  different,  is  immediately  recognized.  We  have  not 
to  do  here  with  a  matter  of  the  understanding  or  of  reflexion, 
but  with  one  of  sensation.  In  the  same  manner  that 
bodies  of  different  colors  may  possess  the  same  spatial 
form,  so  here  we  have  two  tonal  entities  which,  acoustically, 
are  differently  colored,  but  possess  the  same  temporal 
form.  As  in  the  one  case  we  pick  out  by  an  immediate 
act  of  feeling  the  identical  components  of  the  space-sensa- 
tion, so  here  we  immediately  detect  the  identical  components 
of  the  time-sensation,  or  the  sameness  of  the  rhythm. 

It  is  of  course  only  for  small  times  that  I  hold  that  there 


THE  ANALYSIS  OF  SENSATIONS        249 

is  an  immediate  sensation  of  time.  We  judge  and  estimate 
longer  times  by  remembering  the  processes  that  took  place 
in  them, — that  is  to  say,  by  splitting  them  up  into  the 
smaller  parts  of  which  we  had  an  immediate  sensation. 


On  hearing  a  number  of  strokes  of  a  bell,  which  are 
exactly  alike  acoustically,  I  discriminate  between  the  first, 
second,  third,  and  so  on.  Is  it  perhaps  the  accompanying 
thoughts,  or  other  accidental  sensations,  with  which  the 
strokes  of  the  bell  happen  to  be  associated,  that  produce 
these  distinguishing  marks?  I  do  not  believe  that  any 
one  will  seriously  uphold  this  view  How  uncertain  and 
unreliable,  if  this  view  were  true,  would  our  measurement 
of  time  be  !  What  would  become  of  it  if  that  accidental 
background  of  thought  and  sensation  should  suddenly 
vanish  from  memory? 

While  I  am  reflecting  upon  something,  the  clock  strikes, 
but  I  give  no  heed  to  it.  After  it  has  finished  striking,  it 
may  be  of  importance  to  me  to  count  the  strokes.  And 
as  a  fact,  there  arise  in  my  memory  distinctly  one,  two, 
three,  four  strokes.  1  give  here  my  whole  attention  to  this 
recollection,  and  by  this  means  the  subject  on  which  I  was 
reflecting  during  the  striking  of  the  clock,  for  the  moment 
completely  vanishes  from  me.  The  supposed  background 
against  which  I  could  note  the  strokes  of  the  bell,  is  now 
wanting  to  me.  By  what  mark,  then,  do  I  distinguish  the 
second  stroke  from  the  first  ?  Why  do  I  not  regard  all 
the  strokes,  which  in  other  respects  are  identical,  as  one  ? 
Because  each  is  connected  for  me  with  a  special  time- 


250        THE  ANALYSIS  OF  SENSATIONS 

sensation  which  starts  up  into  consciousness  along  with  it. 
In  like  manner,  I  distinguish  a  memory-image  from  a 
creation  of  fancy  by  a  specific  time-sensation  which  is  not 
that  of  the  present  moment. 


Since,  so  long  as  we  are  conscious,  time-sensation  is 
always  present,  it  is  probable  that  it  is  connected  with  the 
organic  consumption  necessarily  associated  with  conscious- 
ness,— that  we  feel  the  work  of  attention  as  time.  During 
any  severe  effort  of  attention  time  is  long  to  us,  during 
easy  employment  short.  When  we  are  in  a  dull. state, 
hardly  noticing  our  surroundings,  the  hours  pass  rapidly 
away.  When  our  attention  is  completely  exhausted,  we 
sleep.  In  dreamless  sleep,  the  sensation  of  time  is  lacking. 
When  profound  sleep  intervenes,  yesterday  is  connected 
with  to-day  only  by  an  intellectual  bond,  apart  from  the 
feeling  common  to  both  that  remains  the  same. 

I  have  already  on  a  former  occasion  referred  to  the 
apparent  difference  of  the  ways  in  which  animals  of 
different  sizes  measure  time.1  But  the  measurement  of 
time  seems  to  change  with  age  as  well.  How  short  the  days 
seem  to  me  now  in  comparison  with  the  days  of  my  youth  ! 
And  in  my  youth  I  used  to  watch  an  astronomical  clock 
that  struck  the  seconds ;  when  I  think  of  that  clock  now, 
the  second-stroke  seems  to  be  appreciably  accelerated.  I 
cannot  shake  off  the  impression  that  my  physiological  time- 
unit  has  become  larger. 

The  fatiguing  of  the  organ  of  consciousness  goes  on  con- 
1  Zeitsinn  des  OAres,  p.  17. 


THE  ANALYSIS  OF  SENSATIONS        251 

tinually  in  waking  hours,  and  the  labor  of  attention  increases 
just  as  continuously.  The  sensations  connected  with 
greater  expenditure  of  attention  appear  to  us  to  happen 
later. 

Normal  as  well  as  abnormal  psychical  events  appear  to 
accord  with  this  conception.  Since  the  attention  cannot  be 
fixed  upon  two  different  sense-organs  at  once,  the  sensa- 
tions of  two  organs  can  never  occur  together  and  yet  be 
accompanied  by  an  absolutely  identical  effort  of  attention. 
Hence,  the  one  appears  later  than  the  other.  Something 
analogous  to  the  so-called  personal  equation  of  astronomers, 
having  its  ground  in  analogous  facts,  is  also  frequently 
observed  in  the  same  sense-province.  It  is  a  well-known 
fact  that  an  optical  impression  which  arises  physically  later 
may  yet,  under  certain  circumstances,  appear  to  occur 
earlier.  It  sometimes  happens,  for  example,  that  a  surgeon, 
in  bleeding,  first  sees  the  blood  spirt  out  and  afterwards  his 
lancet  enter.1  Dvorak  has  shewn,2  in  a  series  of  experi- 
ments which  he  carried  out  at  my  desire,  years  ago,  that 
this  relation  may  be  produced  at  will,  the  object  on  which 
the  attention  is  centred  appearing  (even  when  it  is  really 
from  1/8  to  1/6  of  a  second  later)  earlier-  than  that  indirectly 
seen.  It  is  quite  possible  that  the  familiar  experience  of 
the  surgeon  may  find  its  explanation  in  this  fact.  The  time 
which  the  attention  requires  to  turn  from  one  place  at  which 
it  is  occupied,  to  another,  is  shewn  in  the  following  experi- 

1  Compare     Fechner,     Psychophysik^       Leipzig,    1860,     Vol.     II., 

P-  433- 

2  Dvorak,   u  Ueber  Analoga    der   persb'nlichen   Differenz  zwischen 
beiden  Augen  und  den  Netzhautstellen  desselben  Auges,"     Sitzbcr.  d. 
konigl,  bohm.  Gesellschaft  der  Wissenschaften  (Math-naturw.  Classe), 
March  8,  1872, 


252 


THE  ANALYSIS  OF  SENSATIONS 


green 


red 


ment  instituted  by  me.1  Two  bright  red  squares  measuring 
two  centimeters  across  and  situated  on  a  black  background 
eight  centimeters  apart,  are  illuminated  in  a  perfectly  dark 
room  by  an  electric  spark  concealed  from  the  eye.  The 
square  directly  seen  appears  red,  but  that  indirectly  seen 

appears  green,— ^and  often  quite 
intensely  so.  The  retarded 
attention  finds  the  indirectly 
seen  square  when  it  is  already 
in  the  stage  of  Purkinje's  positive 
after-image.  A  Geissler's  tube 
with  two  bright  red  spots  at  a 
short  distance  from  one  another, 
exhibits,  on  the  passage  of  a  single  discharge,  the  same 
phenomenon.2 

The  reader  must  be  referred  for  details  to  Dvorak's  paper. 
Of  particular  interest  are  his  experiments  on  the  stereoscopic 
(binocular)  combination  of  non-simultaneous  impressions.3 
More  recently  Sandford 4  and  Miinsterberg 5  have  carried 
out  experiments  of  this  kind. 


indir.  seen 


dir.  seen 


Fig.  34- 


I  have  repeatedly  observed  an  interesting  phenomenon 
which  should  be  cited  here.     I  have  been  sitting  in  my 

1  Communicated  by  Dvorak,  loc.  cit. 

-G.  Heymans  could  not  succeed  at  first  in  this  latter  experiment, 
but  has  subsequently  convinced  himself  of  the  correctness  of  my 
statement. 

3  Op.  cit. ,  p.  2. 

*  Sandford,  American  journal  of  Psychology,  1894,  Vol.  VI.,  p.  576. 

5  Miinsterberg,  Psychological  Reviezv,  1894,  Vol.  I.,  p.  56. 


THE  ANALYSIS  OF  SENSATIONS        253 

room,  absorbed  in  work,  while  in  an  adjacent  room  experi- 
ments in  explosions  were  being  carried  on.  It  regularly 
occurred  that  I  shrank  back  startled,  before  I  heard  the  report. 
Since  the  attention  is  especially  inert  in  dreams,  naturally 
the  most  peculiar  anachronisms  occur  in  this  state,  as  every 
one  has  doubtless  observed.  For  instance,  we  dream  of  a 
man  who  rushes  at  us  and  shoots,  awake  suddenly,  and  per- 
ceive the  object  which,  by  its  fall,  has  produced  the  entire 
dream.  Now  there  is  nothing  absurd  in  assuming  that  the 
acoustic  stimulus  enters  simultaneously  different  nerve- 
tracks  and  is  met  there  by  the  attention  in  some  inverted 
order,  just  as,  in  the  case  above  mentioned,  I  perceived 
first  the  general  excitation  and  afterwards  the  report  of  the 
explosion.  But  in  many  cases  it  is  undoubtedly  a  sufficient 
explanation  to  assume  the  interweaving  of  a  sensation  with 
the  framework  of  a  dream  already  present. 


6. 

If  organic  consumption,  or,  for  that  matter,  the  accumula- 
tion of  fatigue-material  were  immediately  felt,  we  might 
logically  expect  a  reversal  of  time  in  dreams.  The  diffi- 
culty disappears  if  consumption  and  restitution  are  regarded 
as  heterodromous  processes  in  Pauli's  sense  (see  p.  68  above). 
The  eccentricities  of  dreams  may  all  be  accounted  for  by 
the  fact  that  many  sensations  and  representations  do  not 
enter  consciousness  at  all,  while  others  enter  with  too  much 
difficulty  and  too  late.  Inertia  of  association  is  a  funda- 
mental feature  of  dreams.  The  intellect  often  sleeps  only 
in  part.  We  converse  very  sensibly,  in  dreams,  with  persons 
long  dead,  but  with  no  recollection  of  their  death.  I 


254        THE  ANALYSIS  OF  SENSATIONS 

speak  to  a  friend  of  a  third  person,  and  this  friend  is  him- 
self the  third  person  of  whom  I  was  speaking.  We  reflect, 
in  the  dream-state,  concerning  dreams,  and  recognize  them 
as  such  by  their  eccentricities,  which  then  at  once  cease  to 
disturb  us.  I  once  dreamed  very  vividly  of  a  mill.  The 
water  flowed  downwards,  in  a  sloping  channel,  away  from  the 
mill,  and  close  by,  in  just  such  another  channel,  upwards 
to  the  mill.  I  was  not  at  all  disturbed  by  the  contradic- 
tion.— At  a  time  when  much  engrossed  with  the  subject 
of  space-sensation,  I  dreamed  of  a  walk  in  the  woods. 
Suddenly  I  noticed  the  defective  perspective  displacement 
of  the  trees,  and  by  this  recognized  that  I  was  dreaming. 
The  missing  displacements,  however,  were  immediately 
supplied. — Again,  while  dreaming,  I  saw  in  my  laboratory 
a  beaker  filled  with  water,  in  which  a  candle  was  serenely 
burning.  "  Where  does  it  get  its  oxygen  from  ?  "  I  thought. 
11  It  is  absorbed  in  the  water,"  was  the  answer.  "  Where 
do  the  gases  produced  in  the  combustion  go  to?"  The 
bubbles  from  the  flame  mounted  upwards  in  the  water, 
and  I  was  satisfied.  W.  Robert  l  has  made  the  excellent 
observation  that  it  is  principally  perceptions  and  thoughts, 
which  owing  to  some  interruption  we  have  been  unable  to 
carry  to  a  conclusion  during  the  day,  of  which  the  thread 
is  taken  up  in  dreams.  And  as  a  matter  of  fact  we  fre- 
quently draw  the  elements  of  our  dreams  from  the  events 
of  the  preceding  day.  Thus  I  used  to  be  able  to  refer, 
with  almost  complete  certainty,  the  dream  about  the  light 
in  the  water  to  a  certain  experiment  in  my  lectures  with  an 
electric  carbon-light  under  water,2  and  the  dream  about 

1  W.  Robert,  Ueber  den  Traum,  Hamburg,  1886. 
*  Prinzipien  der  Warmelehre>  2nd  ed.,  1900,  p.  444. 


THE  ANALYSIS  OF  SENSATIONS        255 

the  mill  to  my  experiments  with  the  apparatus  described  on 
p.  143  (Fig.  19)  above.  Visual  hallucinations  play  the  prin- 
cipal part  in  my  dreams.  I  have  acoustic  dreams  less  often, 
though  I  clearly  hear  conversations,  the  sound  of  bells,  and 
music  in  my  dreams.1  Every  sense,  even  the  sense  of  taste, 
can  come  into  play  in  dreams,  though  some  more  rarely 
than  others.  Since  reflex  excitability  is  greatly  heightened 
in  the  dream-state,  and  the  conscience  on  the  other  hand 
very  much  weakened  owing  to  the  inertia  of  association, 
one  is  capable  of  almost  any  crime  in  dreams,  and  at  the 
stage  of  waking  may  go  through  the  acutest  torments. 
Anyone  who  allows  such  experiences  to  affect  him,  must 
entertain  grave  doubts  as  to  the  Tightness  of  our  method  of 
exercising  justice,  which  consists  in  making  good  one  misery 
by  a  second,  the  second  being  added  to  the  first  by  means 
of  a  process  that  is  revolting  because  deliberate,  cruel,  and 
solemn. 

I  should  not  like  to  let  this  opportunity  slip  of  recommend- 
ing to  the  reader  the  excellent  book  of  M.  de  Manaceine.2 
What  was  said  above  as  to  the  inadequacy  of  temporary 
associations  as  an  explanation  of  psychical  life  (see  pp.  201, 
239,  240)  holds  for  the  dream-state  also.  We  have  to  add 
that  the  faintest  traces  of  something  which  has  long  been 
forgotten  for  the  waking  consciousness,  the  slightest  disturb- 
ances of  health  and  disposition  which  have  to  fall  into  the 
background  during  the  bustle  of  the  day,  can  make  them- 
selves felt  in  dreams.  In  his  Philosophic  der  Mystik  (1885, 
p.  123)  Du  Prel  poetically  compares  this  process  with  the 

1  Wallaschek,  "Das  musikalische  Gedachtnis,"    Vierteljahrsschrift 
fiir  Musikivissenschaft,  1882,  p.  204. 

2  M.  de  Manac6ine,  Sleep,  its  Physiology ',  etc.,  London,  1897. 


256        THE  ANALYSIS  OF  SENSATIONS 

way  in  which  the  faintly  glimmering  starry  firmament  be- 
comes visible  when  the  sun  has  set.  This  book  contains 
many  passages  of  remarkable  and  profound  insight.  The 
man  of  science,  in  particular,  whose  critical  sense  is  directed 
towards  the  nearest  practicable  object  of  research,  reads  it 
with  pleasure  and  profit,  without  allowing  himself  to  be  led 
astray  by  the  author's  inclination  towards  the  fantastic,  the 
miraculous  and  the  extraordinary. 


If  time-sensation  is  connected  with  the  growth  of  organic 
consumption  or  with  the  equally  continuous  growth  of  the 
effort  following  upon  attention,  then  we  can  understand  why 

physiological   time  is   not   re- 
versible,  any  more  than  physi- 

I     f  1     i      cal  time,  but  moves  only  in  one 

direction.     As  long  as  we  are 

in  the  waking  state,  consumption  and  the  labor  of  attention 
can  only  increase,  not  diminish.  The  two  accompanying 
bars  of  music,  which  present  a  symmetry  to  the  eye  and 
to  the  understanding,  shew  nothing  of  the  sort  as  regards 
the  sensation  of  time.  In  the  province  of  rhythm,  and  of 
time  in  general,  there  is  no  symmetry. 


8. 

It  is  perhaps  an  obvious  and  natural,  though  still  an  im- 
perfect conception,  to  regard  the  "  organ  of  consciousness  " 
as  capable,  in  a  small  degree,  of  all  the  specific  energies,  of 
which  each  sense-organ  is  able  only  to  display  a  few.  Hence 


THE  ANALYSIS  OF  SENSATIONS        257 

the  shadowy  and  evanescent  character  of  representation  as 
compared  with  sensation,  through  which  it  must  be  con- 
stantly nourished  and  refreshed.  Hence  also  the  capacity 
of  the  organ  of  consciousness  to  serve  as  a  bridge  of 
connexion  between  all  sensations  and  memories.  With 
every  specific  energy  of  the  organ  of  consciousness,  we 
should  then  have  to  conceive  still  another  particular  energy, 
the  sensation  of  time,  associated,  so  that  none  of  the  former 
could  be  excited  without  the  latter.  Should  this  new  energy 
appear  physiologically  superfluous  and  only  invented  ad  hoc, 
we  might  at  once  assign  to  it  an  important  physiological 
function.  What  if  this  energy  kept  up  the  flow  of  blood 
that  nourishes  the  brain-parts  in  their  work,  guided  this 
current  to  its  destination,  and  regulated  it  ?  Our  con- 
ception of  attention  and  of  time-sensation  would  then 
receive  a  very  material  basis.  The  fact  that  there  is 
only  one  cohering  time,  too,  would  become  intelligible, 
since  the  partial  attention  given  to  one  sense  is 
always  drawn  from  the  total  attention,  and  is  determined 
by  it. 

Such  a  theory  is  strongly  suggested  by  Mosso's  work  on 
plethysmography  and  by  his  observations  on  the  circulation 
of  the  blood  in  the  brain.1  William  James  gives  a  cautious 
assent  to  this  conjecture.2  James  indicates  that  it 
would  be  desirable  to  put  it  into  a  more  definite  and 
detailed  form,  but  I  have  unfortunately  not  been  able  to 
do  this. 


1  Mosso,  Kreislauf  dcs  Bhites  im  Gehirn,  Leipzig,  1881.     Cf.  also 
Kornfeld,  Ueber  die  Beziehiing  von  Atmung  und  Kreislauf  zur  geistigen 
Arbeit,  Briinn,  1896. 

2  W.  James,  Psychology,  Vol.  I.,  p.  635. 

R 


258        THE  ANALYSIS  OF  SENSATIONS 


In  listening  to  a  number  of  similar  strokes  from  a  bell, 
we  can  distinguish  each  from  the  others  in  memory  and 
also  count  them  in  memory,  provided  they  are  few  in 
number.  If  the  number  is  large,  however,  we  distinguish 
the  last  ones  from  one  another,  but  not  the  first.  In  this 
case,  if  we  would  not  make  a  mistake,  we  must  count  them 
immediately  upon  their  being  sounded,  that  is,  we  must 
voluntarily  connect  each  stroke  with  an  ordinal  symbol. 
The  phenomenon  is  perfectly  analogous  to  that  which  we 
observe  in  the  province  of  the  space-sense,  and  is  to  be 
explained  on  the  same  principle.  In  walking  forwards,  we 
have  a  distinct  sensation  that  we  are  moving  away  from  a 
starting-point,  but  the  physiological  measure  of  this  removal 
is  not  proportional  to  the  geometrical.  In  the  same 
manner,  elapsed  physiological  time  is  subject  to  perspectival 
contraction,  its  single  elements  becoming  less  and  less 
distinguishable.1 

10. 

If  a  special  time-sensation  exists,  it  goes  without  saying 
that  the  identity  of  two  rhythms  will  be  immediately  re- 
cognized. But  we  must  not  leave  the  fact  unnoticed  that 
two  rhythms  which  are  the  same  physically  may  appear 
very  different  physiologically,  just  as  the  same  space-figure 
by  change  of  position  may  give  rise  to  different  physio- 
logical space-forms.  The  rhythm  represented  by  the 
following  notes,  for  example,  appears  quite  different  accord- 
1  Cp.  p.  134. 


THE  ANALYSIS  OF  SENSATIONS        259 

ing  as  we  regard  the  short  thick,  or  the  long  thin  vertical 
lines,  or  the  dotted  lines,  as  marking  the  bars.  Evidently 
this  is  connected  with  the  fact  that  the  attention  (guided  by 
the  accent)  sets  in  at  i,  2,  or  3,  that  is,  that  the  sensations 


nn 


of  time  corresponding  to  the  successive  beats  are  compared 
with  different  initial  sensations. 

When  all  the  times  of  a  rhythm  are  prolonged  or 
shortened,  a  similar  rhythm  arises,  which,  however,  can  only 
be  felt  as  similar  when  the  prolongation  or  shortening  does 
not  exceed  the  limit  imposed  by  the  immediate  sensation 
of  time. 

The  rhythm  represented  in  the  following  diagram  appears 
physiologically  similar  to  the  preceding,  but  only  when 
similarly-marked  bars  are  taken  in  the  two — that  is,  when 


the  attention  sets  in  at  homologous  points  of  time.  Two 
physical  time-constructions  may  be  termed  similar  when  all 
the  parts  of  the  one  stand  in  the  same  relation  to  one 
another  as  do  the  homologous  parts  of  the  other.  But 
physiological  similarity  makes  its  appearance  only  when  the 
above  condition  is  likewise  fulfilled.  Furthermore,  so  far  as 
I  am  able  to  judge,  we  recognize  the  identity  of  the  time- 
ratios  of  two  rhythms  only  when  the  same  are  capable  of  _. 
being  represented  by  very  small  whole  numbers.  Thus  we 


260        THE  ANALYSIS  OF  SENSATIONS 

really  notice  immediately,  only  the  identity  or  non-identity 
of  two  times,  and,  in  the  latter  case,  we  recognize  the  ratio 
of  the  two  only  by  the  fact  that  one  part  is  exactly  contained 
in  the  other.  Herewith  we  have  an  explanation  of  the  fact 
that,  in  marking  time,  the  time  is  always  divided  into 
absolutely  equal  parts.1 

The  conjecture  thus  forces  itself  upon  us,  that  the  sensa- 
tion of  time  is  closely  connected  with  periodically  or 
rhythmically  repeated  processes.  But  it  is  scarcely  capable 
of  being  proved,  though  the  attempt  has  been  made  in  some 
quarters,  that  the  measurement  of  time  in  general  is  based 
on  breathing  or  on  the  pulse.  These  questions,  however, 
are  by  no  means  simple.  Many  processes,  of  course,  take 
place  rhythmically  in  the  bodies  of  animals,  without  it 
being  possible  for  us  to  attribute  to  them  any  particular 
sense  for  time,  rhythm  or  beat.  When  a  pair  of  horses  is 
driven  past  my  house,  I  can  hear  for  a  long  time  the 
coincidence  and  alternation  of  the  hoof-beats  of  the  two 
horses  fading  away  into  the  distance  in  regular  periods. 
Thus  each  horse  keeps  to  its  own  time  without  troubling 
about  that  of  the  other  horse,  and  without  adapting  itself  to 
the  other.  Two  men  harnessed  together  would  find  this 
almost  intolerable.  Wallaschek  mentions  the  deficiency 
of  the  sense  of  time  in  horses,  and  also  the  difficulty  of 
keeping  up  the  appearance  of  it  in  circus  performances.  It 
can  scarcely  be  upon  the  coarser  bodily  processes  that  the 
feeling  for  time  is  immediately  based.  Probably  it  must  be 
referred  rather  to  a  superior  psychical  sensibility,  in  virtue 
of  which  a  trifling  psychical  circumstance  determines  the 

1  The  similarity  of  space-figures  would  be  felt,  according  to  this  theory, 
much  more  immediately  than  the  similarity  of  rhythms. 


THE  ANALYSIS  OF  SENSATIONS        261 

attention  to  notice  an  otherwise  indifferent  process.  But 
when  processes  that  keep  time  are  carefully  observed, — and 
such  observation  always  involves  a  certain  amount  of  co- 
operation and  imitation, — the  psychical  functions,  and 
finally  the  coarser  bodily  functions  themselves  also,  then 
become  adapted  to  the  time.1 

Dr.  R.  Wlassak  has  communicated  to  me  in  conversation 
a  remark  which  I  will  reproduce  in  his  own  words : 

"When  the  sensations  are  connected  with  a  vivid 
emotional  coloring,  time-values  are  always  markedly  dimin- 
ished ;  this  fact  accords  with  the  hypothesis  that  the  sensa- 
tion of  time  depends  on  organic  consumption.  Xhe  rule 
holds  both  for  stretches  of  time  that  are  filled  with  strongly 
pleasurable  sensations  and  for  those  filled  with  unpleasant 
sensations.  On  the  other  hand,  the  sensations  that  oscillate 
round  the  indifference-values  of  emotional  coloring  are  con- 
nected with  relatively  indistinct  sensations  of  time.  These 
facts  indicate  that  the  nervous  processes  belonging  to  the 
sensations  of  time  and  to  the  emotions  respectively  offer 
certain  analogies. 

In  point  of  fact,  all  attempts  to  frame  a  ^physiological 
theory  of  the  emotions  bring  the  emotions  into  relation  with 
consumption;  as  is  done,  for  instance,  in  Meynert's  or  in 
Avenarius'  theory  of  the  emotions." 

1  Wallaschek,  Anfilnge  der  Tonkunst,  Leipzig,  1903,  pp.  270,  271. 
This  book,  a  profusely  illustrated  German  edition  of  an  English  book 
by  the  same  author  (Primitive  Music,  London,  1903),  contains  many 
very  valuable  observations  on  the  questions  discussed  in  this  and  the 
following  chapters. 


XIII.  SENSATIONS   OF   TONE.1 


i. 

AS  regards  tone-sensations,  also,  we  are  restricted  mainly 
to  psychological  analysis.     As  before,  the  beginning 
of  an  investigation  is  all  we  can  offer. 

Among  the  sensations  of  tone  possessing  greatest  im- 
portance for  us  are  those  excited  by  the  human  voice,  as 
utterances  of  pleasure  and  pain,  of  expressions  of  the  will, 
and  of  the  communication  of  thoughts  by  speech,  etc.  Nor 
can  there  be  any  doubt  that  the  voice  and  the  organ  of 
hearing  bear  a  close  relation  to  each  other.  The  simplest 
and  distinctest  form  in  which  sensations  of  tone  reveal  their 
remarkable  characteristics  is  music.  Will,  emotion,  the 
expression  of  sound,  and  the  sensation  of  sound,  have 
certainly  a  strong  physiological  connexion.  There  is  a 
good  deal  of  truth  in  the  remark  of  Schopenhauer 2  that 
music  represents  the  will,  and  in  fact  generally  in  the 

"*  Apart  from  details,  I  have  held  the  position  here  taken  up  since  1865. 
Stumpf,  whom  I  must  here  thank  for  the  repeated  consideration  of  my 
work,  has  many  points  of  detail  (Tonpsychologie,  Leipzig,  1883,  Vol.  I.) 
that  appeal  to  me.  The  view  expressed  on  page  1 19  of  his  work,  how- 
ever, seemed  incompatible  with  the  principle  of  parallelism,  my 
fundamental  axiom  of  research ;  though  the  remark  which  he  directs 
against  Lipps  (Beitrdge  zur  Akuitik,  Vol.  I.,  p.  47,  footnote),  repre- 
sents an  approximation  to  my  point  of  view.  Compare  my  note,  "  Zur 
Analyse  der  Tonempfindungen,"  Sitzungsberichte  der  Wiener  Akademie^ 
Vol.  XCIL,  II.  Abth.,  p.  1282  (1895). 

8  Schopenhauer,  Die  Welt  als  Wille  tind  Vorstelhtng. 
262 


THE  ANALYSIS  OF  SENSATIONS        263 

designation  of  music  as  a  language  of  emotion ;  although 
this  is  scarcely  the  whole  truth. 


2. 


Following  the  precedent  of  Darwin,  H.  Berg  has,  to  put 
it  shortly,  attempted  to  derive  music  from  the  amatory  cries 
of  monkeys.1  We  should  be  blind  not  to  recognize  the 
service  rendered  and  enlightenment  conveyed  by  the  work 
of  Darwin  and  Berg.  Even  at  the  present  day,  music  has 
power  to  touch  sexual  chords,  and  is,  as  a  fact,  widely  made 
use  of  in  courtship.  But  as  to  the  question  wherein  con- 
sists the  agreeable  quality  of  music,  Berg  makes  no  satis- 
factory answer.  And  seeing  that  in  musical  theory  he 
adopts  Helmholtz's  position  of  the  avoidance  of  beats  and 
assumes  that  the  males  who  howled  least  disagreeably 
received  the  preference,  we  may  be  justified  in  wondering 
why  the  most  intelligent  of  these  animals  were  not  prompted 
to  maintain  silence  altogether. 

The  importance  of  tracing  the  connexion  of  a  given 
biological  phenomenon  with  the  preservation  of  the  species, 
and  of  indicating  its  phylogenetic  origin,  cannot  be  under- 
rated. But  we  must  not  imagine  that  in  having  accomplished 
this  we  have  solved  all  the  problems  connected  with  the 
phenomenon.  Surely  no  one  will  think  of  explaining  the 
element  of  pleasure  in  the  specific  sexual  sensation  by  show- 
ing its  connexion  with  the  preservation  of  the  species.  We 
should  be  more  likely  to  acknowledge  that  the  species  is 
preserved  because  the  sexual  sensation  is  pleasurable. 
Although  music  may  actually  remind  our  organism  of  the 
1  H.  Berg,  Die  Lust  an  der  Musik,  Berlin,  1879. 


264        THE  ANALYSIS  OF  SENSATIONS 

courtship  of  distant  progenitors,  it  must,  if  it  was  ever  used 
for  wooing,  have  contained  at  the  start  some  positive 
agreeable  quality,  which,  to  be  sure,  may  be  reinforced  at 
the  present  time  by  that  memory.  To  take  an  analogous 
case  from  individual  life,  the  smell  of  an  oil-lamp  as  it  goes 
out  almost  always  agreeably  reminds  me  of  the  magic  lantern 
which  excited  my  wonder  as  a  child.  Yet  in  itself  the 
smell  of  the  lamp  is  none  the  less  disgusting  for  this  reason. 
Nor  does  the  man  who  is  reminded,  by  the  scent  of  roses, 
of  a  pleasant  experience,  believe,  on  this  account,  that  the 
scent  was  not  previously  agreeable.  It  has  only  gained  by 
the  association.1  And  if  the  view  in  question  cannot 
sufficiently  explain  the  agreeable  quality  of  music  per  se,  it 
assuredly  can  contribute  still  less  to  the  solution  of  special 
questions,  as,  for  instance,  why,  in  a  given  case,  a  fourth 
is  preferred  to  a  fifth. 


A  rather  one  sided  view  of  the  sensations  of  tone  would 
be  obtained  if  we  were  to  consider  only  the  province  of 
speech  and  music.  Sensations  of  tone  are  not  only  a 
means  of  communicating  ideas,  of  expressing  pleasure  and 
pain,  of  discriminating  between  the  voices  of  men,  women, 
and  children ;  they  are  not  mere  signs  of  the  exertion  or 
passion  experienced  by  the  person  speaking  or  calling; 
they  also  constitute  the  means  by  which  we  distinguish 
between  large  and  small  bodies  when  sounding,  between 
the  tread  of  large  and  small  animals.  The  highest  tones, 
the  very  ones  which  the  vocal  organs  of  man  cannot  pro- 

1  Fechner,  notably,  has  emphasized  the  significance  of  association 
for  aesthetics. 


THE  ANALYSIS  OF  SENSATIONS        265 

duce,  presumably  are  of  extreme  importance  for  the  deter- 
mination of  the  direction  from  which  sounds  proceed.1  In 
fact,  it  is  more  than  likely  that  these  latter  functions  of 
sensations  of  tone  antedated,  in  the  animal  world,  by  a  long 
period,  those  which  merely  perform  a  part  in  the  social  life 
of  animals.  By  inclining  a  piece  of  cardboard  in  front  of 
the  ear,  anyone  can  convince  himself  that  it  is  only  those 
noises  which  contain  very  high  tones,  such  as  the  rustling 
and  hissing  of  a  gas  flame,  of  a  steam  kettle,  or  of  a  water- 
fall, that  are  modified  by  reflexion  according  to  the  position 
of  the  cardboard,  and  that  deep  tones  remain  entirely 
uninfluenced.  This  shews  that  it  is  only  in  virtue  of  their 
effect  on  high  tones  that  the  two  ear-conchs  can  be 
used  as  indicators  of  direction.2 


There  is  no  one  but  will  cheerfully  acknowledge  the 
decided  advance  effected  by  Helmholtz  in  the  analysis  of 
auditory  sensations,3  following  on  the  important  works  of 
his  predecessors,  Sauveur,  Rameau,  R.  Smith,  Young,  Ohm, 

1  Mach,    "  Bemerkungen    liber    die    Function    der    Ohrmuschel " 
(Troltsch's  Archiv  Jur  Ohrenheilkunde,  New  Series,  Vol.  III.,  p   72). 
— Compare  also  Mach  and  Fischer,   "Die  Reflexion   und   Brechurig 
des  Schalles,   Fogg.  Ann.,  Vol.    CXLIX.,  p.    221;    A.  Steinhauser, 
Theorie  des  binaurealen  Horens,  Vienna,  1877. 

2  I  once  had  occasion  to  observe  that  tame  marmots  that  were  quite 
insensible   to  deep   and  loud   noises,   were   suddenly  frightened,  and 
always  rushed  into  hiding,  whenever  anyone  produced  a  high-pitched 
noise  by  rubbing  straw  or  crackling  paper.     Children  a  few  months  old 
are  also  very  sensitive  to  such  noises. 

3  Helmholtz,  Die  Lehre  von  den  l^onempfindungen,  1st  ed. ,  Bruns- 
wick, 1863. 


266        THE  ANALYSIS  OF  SENSATIONS 

and  others.1  Following  his  principles,  we  recognize  in 
noises  combinations  of  musical  tones,  of  which  the  number, 
pitch,  and  intensity  vary  with  the  time.  In  compound 
musical  sounds,  or  clangs,  we  generally  hear,  along  with  the 
fundamental  n,  the  over-tones  or  partial  tones"  2n,  $n,  471, 
etc.,  each  of  which  corresponds  to  simple  pendular  vibra- 
tions. If  two  such  musical  sounds,  to  the  fundamentals 
of  which  the  rates  of  vibration  n  and  m  correspond,  be 
melodically  or  harmonically  combined,  there  may  result, 
if  certain  relations  of  n  and  m  are  satisfied,2  a  partial  coin- 
cidence of  the  harmonics,  whereby  in  the  first  case  the 
relationship  of  the  two  sounds  is  rendered  perceptible,  and 
in  the  second  a  diminution  of  beats  is  effected.  All  this 
cannot  be  disputed,  although  it  may  not  be  considered 
exhaustive. 

We  may  also  give  our  assent  to  Helmholtz's  physiological 
theory  of  audition.  The  facts  observed  on  the  simultaneous 
sounding  of  simple  notes  make  it  highly  probable  that  there 
exists,  corresponding  to  the  series  of  vibration-rates,  a  series 
of  terminal  nervous  organs,  so  that  for  all  the  different  rates 
of  vibration  there  are  different  end-organs,  each  of  which 
responds  to  only  a  few,  closely  adjacent  rates  of  vibration. 
On  the  other  hand,  Helmholtz's  physical  theories  as  to  the 
function  of  the  labyrinth  have  proved  untenable.  I  shall 
return  to  this  point. 

5- 

If  we  assume  with   Helmholtz  that  all  noises  admit  of 
1  Cp.  "  Zur  Geschichte  der  Akustik  "  in  my  Popiilar-ivissenschoftliche 

Vorlesungen. 
3  The  /th  harmonic  of  n  coincides  with  the  ^th  of  m  when  pn  —-  qmt 

that  is  m  =  (plq)  n,  where/  and  q  are  whole  numbers. 


THE  ANALYSIS  OF  SENSATIONS        267 

being  resolved  into  sensations  of  tone  varying  in  duration, 
it  seems  superfluous  to  seek  further  for  a  special  auditive 
organ  for  noises,  and  Helmholtz  himself  soon  gave  up  so 
inconsequent  a  procedure.  A  long  time  ago  (in  the  winter 
of  1872-73)  I  took  up  the  question  of  the  relation  of  noises 
(especially  that  of  sharp  reports)  to  musical  tones,  and 
found  that  every  degree  of  transition  between  the  two  may 
be  demonstrated.  A  tone  of  one  hundred  and  twenty-eight 
full  vibrations,  heard  through  a  small  radial  slit  in  a  slowly 
revolving  disc,  contracts,  when  its  duration  is  reduced  to 
from  two  to  three  vibrations,  to  a  short,  sharp  concussion 
(or  weak  report)  of  very  indistinct  pitch,  while  with  from 
four  to  five  vibrations,  the  pitch  is  still  perfectly  distinct. 
On  the  other  hand,  with  sufficient  attention,  a  pitch,  though 
not  a  very  definite  one,  may  be  detected  in  a  report  even 
when  the  latter  is  produced  by  an  aperiodic  motion  of  the 
air  (the  wave  of  an  electric  spark,  exploding  soap-bubbles 
filled  with  2ff+  O).  We  may  easily  convince  ourselves, 
furthermore,  that  in  a  piano  from  which  the  damper  has 
been  lifted,  large  exploding  bubbles  mainly  excite  to  sym- 
pathetic vibration  the  lower  strings,  while  small  ones 
principally  affect  the  higher  strings.  This  fact,  it  seems 
clear  to  me,  demonstrates  that  the  same  organ  may  be  the 
mediator  of  both  tone  and  noise  sensation.  We  must 
imagine  that  weak  aperiodic  movements  of  the  air  having 
short  durations  excite  all,  though  preferably  the  small  and 
more  mobile  end-organs,  whilst  more  powerful  and  more 
lasting  movements  of  the  air  excite  the  larger  and  more 
inert  end-organs  as  well,  which  from  being  less  damped 
perform  vibrations  of  greater  amplitude  and  are  thus 
noticed ;  and  furthermore  that  even  in  the  case  of  com- 


268        THE  ANALYSIS  OF  SENSATIONS 

paratively  weak  periodic  movements  of  the  air,  the  stimulus 
appears,  by  an  accumulation  of  effects,  in  some  definite 
member  of  the  series  of  end-organs.1  The  sensation  excited 
by  a  report  of  low  or  high  pitch  is  qualitatively  the  same 
as  that  produced  by  striking  at  once  a  large  number  of 
adjacent  piano-keys  either  high  or  low  in  the  scale,  only 
more  intense  and  of  shorter  duration.  Moreover,  in  the 
single  excitation  produced  by  a  report,  the  beats  connected 
with  periodic  intermittent  excitations  are  eliminated. 

6. 

The  work  of  Helmholtz  excited  general  admiration  on 
its  first  appearance ;  but  of  late  years  it  has  been  subjected 
to  various  critical  attacks,  and  it  almost  seems  to  be  as 
much  underestimated  now  as  it  was  originally  overesti- 
mated. Physicists,  physiologists  and  psychologists  have 
had  nearly  forty  years  in  which  to  test  the  three  several 
sides  of  the  theory,  and  it  would  have  been  a  marvel  if 
they  had  not  found  out  its  weak  spots.  Without  making 
any  pretence  to  completeness,  we  will  now  consider  the 
principal  critical  objections  to  it,  taking  first  together  the 
objections  which  have  been  urged  from  the  physical  and 
physiological  side,  and,  secondly,  those  of  the  psycholo- 
gists. 

1  I  gave  an  account  of  part  of  my  experiments,  which  were  a  con- 
tinuation of  Dvorak's  researches  on  the  after-images  due  to  variations 
of  stimulus  (1870),  in  the  August  number  of  Lotos,  1873.  I  have  never 
before  mentioned  the  experiments  relative  to  the  excitement  of  piano- 
tones  by  explosions.  It  will  not  be  amiss,  perhaps,  if  I  do  so  here. 
Ffaundler,  S.  Exner,  Auerbach,  Briicke,  W.  Kohlrausch,  Abraham 
and  Brtihl,  and  others,  subsequently  treated  the  same  questions  in 
detail,  and  from  various  points  of  view. 


THE  ANALYSIS  OF  SENSATIONS        269 

Helmholtz  assumed,  for  psychological  and  physical 
reasons,  that  the  inner  ear  consists  of  a  system  of  resonators, 
which  singles  out  the  members  of  Fourier's  series,  corre- 
sponding to  the  form  of  vibration  presented,  and  hears 
them  as  partial  tones.  On  this  view,  the  relation  between 
the  phases  of  the  partial  vibrations  can  exert  no  influence 
on  sensation.  As  against  this  view,  Konig,1  an  eminent 
specialist  in  acoustics,  tried  to  prove  that  mere  displacement 
of  the  phases  of  the  partial  pendular  vibrations  causes  a 
change  in  the  sensational  impression  or  "sound-color." 
L.  Hermann,2  however,  succeeded  in  shewing  that  when 
the  direction  of  movement  of  a  phonograph  is  reversed, 
no  change  of  sound-color  results.  According  to  Hermann, 
the  individual  sinuous  bands  of  Konig's  wave-siren  do  not 
produce  any  simple  tones,  and  Konig's  conclusions  must 
therefore  be  based  on  a  mistaken  presupposition.3  This 
difficulty  may  therefore  be  taken  as  removed. 

The  phenomena  connected  with  the  combination  of 
tones  are  not  so  easily  explicable  on  Helmholtz'  point  of 
view.  Young  supposed  that  beats  of  sufficient  rapidity 

1  R.  Konig,  Quelques  experiences  d'acoustique,  Paris,  1882. 

2  L.  Hermann,  "Zur  Lehre  von  der  Klangwahrnehmung,"  Pfliiger's 
Archiv,  Vol.  LVI.,  1894,  p.  467. 

3  As  long  ago  as  1867,  I  instituted  experiments  with  a  special  kind  of 
siren,  very  similar   to  one    of  Konig's   apparatus.     The  casing  of  a 
cylinder  was  fitted  with  rings  in  which  were  cut  wave-shaped  slips  in 
similar  pairs  capable  of  mutual  displacement  towards  one  another,  so 
that  the  intensity  and  the  phase  of  the  partial  tone  under  investigation 
could  be  varied  at  will.     But  it  appeared  on  experiment  that  the  wave- 
shaped  slits  did  not  yield  any  simple  tones  when  air  was  blown  against 
them  through  a  slit  parallel   to  the  ordinate  of  the   waves.     As  my 
apparatus   was  still  pretty  imperfect,  and  did  not  fulfil  its  purpose, 
which  was  to  compound  a  sound  from  partial  tones  of  given  intensity 
and  phase,  I  have  not  published  any  account  of  these  experiments. 


270        THE  ANALYSIS  OF  SENSATIONS 

could  themselves  be  heard  as  tones — that  is  to  say,  that 
they  become  compound  tones.  But  since  it  is  impossible 
to  excite  any  resonator  by  means  of  beats,  to  the  tempo  of 
which  it  is  tuned,  but  only  by  means  of  tones,  it  would  be 
impossible,  on  the  resonance  theory,  to  hear  any  compound 
tones.  Helmholtz  therefore  postulated  at  the  outset  that 
compound  tones  must  either  be  explained  objectively  by 
means  of  powerful  tones  in  virtue  of  the  deviation  of  similar 
vibrations  from  linearity, — or  subjectively  by  means  of 
asymmetrical  or  non-linear  conditions  of  vibration  of  the 
resonating  parts  of  the  inner  ear.  Now  Konig1  failed  to 
prove  the  existence  of  objective  compound  tones,  but 
discovered  on  the  other  hand  that,  even  between  tones 
widely  removed  from  one  another,  there  are  beats  which 
can  invariably  be  heard  as  particular  tones  when  the 
sequence  is  sufficiently  rapid.  Hermann 2  detected  com- 
pound tones  with  co-operating  tones  of  such  feebleness, 
that  the  compound  tones  seem  entirely  inexplicable 
on  Helmholtz'  theory,  either  objectively  or  subjectively. 
Hermann  accordingly  holds  the  view,  associating  himself 

1  Konig,  op.  cit.     He  got  his  tones  by  a  very  powerful  tuning-fork, 
and  I  could  not  help  conjecturing  when  his  book  appeared  that,  in 
connexion  with  his  observations  of  the  beats,  the  overtones  came  into 
play  in  various  ways.     Since  then  Stumpf  has  actually  demonstrated 
the  co-operation  of  such  overtones  ( Wiedemann's  Annalen,  New  Series, 
Vol.  LVII. ,  p.  660).     Thus  the  theory  of  Helmholtz  is  safe  on  this  side. 
Still,  the  objection  remains  that  the  objective  compound  tones  do  not 
exist  (Konig,  Hermann),  and  that   subjective  compound  tones  occur 
in    circumstances   which  are  not   compatible   with  Helmholtz'  theory 
(Hermann).    Cp.  also  M.  Meyer,  "  Zur  theorie  der  Differenztone  und 
der   Gehorsempfindungen    Ueberhaupt,"    Zeitschrijt  fur  Psychologic. 
Vol.  XVI.,  p.  I. 

2  Hermann,  "  Zur  Theorie  der  Kombinationstone,"  Pfliiger's  Archiv, 
Vol.  XLIX.,  1891,  p.  499. 


THE  ANALYSIS  OF  SENSATIONS        271 

on  this  point  with  Konig,  that  the  ear  re-acts,  not  only 
to  wave-shaped  vibrations,  but  also,  with  a  sensation  deter- 
mined by  the  duration  of  the  period,  to  every  kind  of 
periodicity. 

The  physical  resonance-theory  seems,  at  any  rate,  in  its 
original  form,  not  tenable;  but  Hermann1  thinks  that  it 
can  be  replaced  by  a  physiological  resonance-theory.  I 
will  deal  later  with  this  view,  as  well  as  with  Ewald's  new 
physical  theory  of  audition. 


We  now  turn  to  the  principal  objections  brought  against 
Helmholtz  from  psychological  points  of  view.  The  lack  of 
a  positive  factor  in  the  explanation  of  consonance  has  been 
very  generally  felt,  the  mere  absence  of  beats  not  being 
regarded  as  a  sufficient  and  satisfactory  characterization  of 
harmony.  Thus  A.  v.  Oettingen  2  feels  the  want  of  some 
expressed  positive  element  characteristic  of  each  interval 
(p.  30),  and  refuses  to  regard  the  value  of  an  interval  as 
dependent  upon  the  physical  accident  of  the  overtones 
contained  in  the  sounds.  He  believes  that  the  positive 
element  in  question  is  to  be  found  in  the  accompanying 
remembrance  of  the  common  fundamental  tone  (or  tonic), 
as  the  harmonics  of  which  the  composite  notes  or  clangs  of 
the  interval  have  often  occurred,  or  in  the  accompanying 
remembrance  of  the  common  overtone  (or  phonic) 3  belonging 
to  the  two  (pp.  40,  47).  On  the  negative  side  of  his  criticisms 

1  Hermann,  Pfliiger's  Arckiv,  Vol.  LVI. ,  p.  493. 

z  Harmoniesystem  in  dtialer  Entwicklung  (Dorpat,  1 866),  p.  30. 

3  [The  lowest  of  the  harmonics  common  to  all  I  term  the  coincident 
or  phonic  harmonic. — Von  Oettingen,  Harmoniesystem  in  dualer 
Entvoicklung,  p.  32.  Quoted  by  translator.] 


272        THE  ANALYSIS  OF  SENSATIONS 

I  am  in  complete  agreement  with  Von  Oettingen.  But 
"  remembrance  "  does  not  quite  fill  the  need  of  the  theory, 
for  consonance  and  dissonance  are  not  matters  of  represen- 
tative activity,  but  of  sensation.  My  opinion,  therefore, 
is  that  A.  von  Oettingen's  conception  is  physiologically 
inadequate.  His  enunciation  of  the  principle  of  duality, 
however  (or  of  the  principle  of  the  tonic  and  phonic 
relationship  of  composite  notes),  as  also  his  conception  of 
dissonances  as  indeterminate  composite  musical  sounds 
admitting  of  more  than  one  interpretation  (p.  224),  appear 
to  me  to  be  valuable  and  positive  services  to  science.1 


8. 

Stumpf  has  in  various  writings  criticized  the  doctrine  of 
Helmholtz  with  great  penetration.2  He  questions,  in  the 
first  place,  the  two  different  definitions  which  Helmholtz 
gives  of  consonance, — the  definition  by  disappearance  of 
beats,  and  the  definition  by  coincidence  of  partial  tones, — 
pointing  out  that  the  former  is  inapplicable  to  and  not 
characteristic  of  melodic  sequence,  and  the  latter  inappli- 
cable to  and  not  characteristic  of  harmonic  combination.  A 

1  A  popular  statement  of  the  principle  of  duality,  of  which  Euler 
Tentamen  novce  theories   tnusica,  p.    103),    D'Alembert   (Elemens  de 
musique-,  Lyons,  1766),  and  Hauptmann  (Die  Natur  der  Harmonik 
und  Metrik,  Leipzig,  1853,  translation  by  W.  E.  Heathcote,  London, 
Swan  Sonnenschein  &  Co.,  1888),  had  all  a  faint  inkling,  is  to  be  found 
in  my  Popular  Scientific  Lectures  (Chicago,  1894),  under  the  caption 
"  Symmetry"  (originally  published  in  1872).     Perfect  symmetry,  such 
as  is  found  in  the  province  of  sight,  cannot  be  imagined  in  music,  since 
sensations  of  tone  do  not  constitute  a  symmetrical  system. 

2  I  am  here  chiefly  following  Stumpf's  Beitrage  zur  Akustik  und 
Musi kwissensc  haft,  Heft  I,  Leipzig,  1898. 


THE  ANALYSIS  OF  SENSATIONS        273 

pure  triple  compound  note,  intermitting  according  to  the 
nature  of  the  beats,  is  not  a  dissonance.  On  the  other 
hand,  examples  can  be  given  of  the  simultaneous  sounding 
of  tones  far  removed  from  one  another,  which  produce  a 
violent  dissonance,  although  the  beats  become  imper- 
ceptible. If  two  notes  of  the  tuning-fork  are  distributed 
one  to  each  ear,  the  beats  do  indeed  sink  very  much  into 
the  background,  but  without  the  distinction  between  con- 
sonance and  dissonance  becoming  any  less.  Subjectively 
heard  tones,  too,  such  as  ringing  in  the  ears,  can  be  experi- 
enced as  dissonances,  of  course  without  the  beats  being 
heard.  Tones,  finally,  that  are  merely  represented,  also 
appear  as  consonant  and  dissonant,  without  the  representa- 
tion of  beats  playing  any  essential  part  in  the  process. 
The  coincidence  of  the  partial  tones  ultimately  disappears, 
when  no  overtones  are  present,  without  necessarily  causing 
the  disappearance  of  the  distinction  between  dissonance 
and  consonance.  I  will  pass  over  Stumpf  s  polemic  against 
the  explanation  of  consonance  by  means  of  unconscious 
counting, — a  view  which  will  probably  find  few  supporters.1 
Equally  readily  will  it  be  admitted  that  agreeableness  is 
not  a  sufficiently  characteristic  property  of  consonance, 
since  it  is  a  property  which  under  certain  circumstances  can 
just  as  well  belong  to  dissonance. 

Stumpf  himself  finds  the  characteristic  mark  of  conson- 

1  Such  explanations  were  attempted  by  Leibniz  and  Euler,  and  have 
been  revived  in  more  recent  times  by  Oppel,  later  by  Lipps  (Psycho- 
logische  Studien,  1885),  and  finally,  in  a  number  of  voluminous  works, 
by  A.  J.  Polak  (  Ueber  Zeiteinheit  in  bezttg  aiij  Konsonanz,  Harmonic 
imd  Tonalitat,  Leipzig,  1900  ;  Ueber  Tonrhythmik  und  Stimmfiihrung, 
Leipzig,  1902  ;  Die  Harmonisierung  indischer,  turkischer  ^^nd  japani- 
scher  Melodien,  Leipzig,  1905). 
S 


274        THE  ANALYSIS  OF  SENSATIONS 

ance  in  the  fact  of  two  tones  when  sounded  together 
approximating,  sometimes  more  and  sometimes  less,  to  the 
impression  of  a  single  tone.  He  defines  consonance  by 
means  of  "  fusion,"  harking  back,  as  it  were,  to  views  pre- 
valent in  antiquity,  of  which  he  gives  an  exhaustive  history.1 
Helmholtz  also  is  not  unfamiliar  with  this  theory ;  he  dis- 
cusses it,  but  thinks  that  he  has  given  the  first  correct 
explanation  of  the  fusion  of  notes. 

Stumpfs  statistical  experiments  shew  that  a  fusion  of 
tones  takes  place  in  consonance.  If  two  tones  are  sounded 
simultaneously,  unmusical  persons  mistake  them  for  a 
single  tone  with  a  frequency  in  proportion  to  the  extent  to 
which  they  are  consonant.  Stumpf  does  not  attempt  to 
conceal  the  necessity  for  some  further  explanation  of  fusion. 
If  it  is  similarity  that  causes  tones  to  fuse,  then  this  must 
be  a  different  kind  of  similarity  from  that  on  which  the 
sequence  of  tones  in  a  series  depends,  since  this  latter 
similarity  decreases  continuously  with  the  distance  of  the 
tones  from  one  another.  But  since  such  a  second  relation 
of  similarity  appears  to  him  purely  hypothetical,  he  prefers 
to  imagine  a  physiological  explanation  of  a  different  kind. 
He  supposes  that,  when  two  tones,  of  which  the  rates  of 
vibration  stand  to  one  another  in  a  comparatively  simple 
ratio,  are  heard  simultaneously,  the  cerebral  processes 
which  take  place  are  connected  by  a  closer  relation  of 
specific  synergy  than  when  the  ratio  of  the  rates  of  vibration 
is  more  complicated.2  Tones  that  succeed  one  another 
can  fuse.  Although  polyphonous  music  is  preceded  his- 

1  C.  Stumpf,  "  Geschichte  des  Konsonanzbegiiffes,"  Abhandlwigen 
der  Munchener  Akademie^  1897. 

2  C.  Stumpf,  Beitriige  zur  Akustik,  Heft  I,  p.  50. 


THE  ANALYSIS  OF  SENSATIONS        275 

torically  by  homophonous,  yet  Stumpf  considers  it  probable 
that  even  in  the  case  of  homophonous  music  the  selection 
of  the  scale  was  guided  by  experience  of  the  simultaneous 
hearing  of  tones.  In  all  essential  points  it  is  impossible 
not  to  agree  with  Stumpf  s  criticism. 


I  myself,  as  early  as  I863,1  and  also  later,2  had  made 
some  critical  remarks  on  the  theory  of  Helmholtz,  and 
in  1866,  in  a  small  work3  which  appeared  shortly  before 
that  of  Von  Oettingen,  I  very  definitely  pointed  out  some 
demands  which  a  more  perfect  theory  of  the  subject  would 
have  to  satisfy.  I  developed  these  remarks  in  more  detail 
in  the  first  edition  of  this  book  (1886). 

Let  us  start  from  the  idea  that  a  .  series  of  definitely 
graduated  end-organs  exists,  the  members  of  which,  as  the 
rate  of  vibration  increases,  successively  yield  their  maximum 
response,  and  let  us  ascribe  to  each  end-organ  its  particular 
(specific)  energy.  Then  there  are  as  many  specific  energies 
as  there  are  end -organs,  and  as  many  rates  of  vibration 
that  we  distinguish  by  the  sense  of  hearing. 

Further,  we  not  only  distinguish  between  tones,  but  we 
also  order  them  in  a  series.  Of  three  tones  of  different 
pitch,  we  recognize  the  middle  one  immediately  as  such. 

1  Mach,  "Zur  Theorie  des  Gehororgans"  (Sitztmgsberichte  der 
Wiener  Akademie,  1863). 

2Cp.  my  "  Bemerkungen  zur  Lehre  vom  raumlichen  Sehen" 
(Fichte's  Zeitschrift  ftir  Philosophic,  1865),  and  see  my  Popular 
Scientific  Lectures. 

3  Einleitung  in  die  Helmholtzsche  Musiktheorie,  Graz,  1 866.  See 
the  Preface  and  pp.  23  et  seq.,  46  and  48. 


276        THE  ANALYSIS  OF  SENSATIONS 


We  feel  immediately  which  rates  of  vibration  lie  nearer 
together  and  which  are  further  apart.  This  is  readily 
enough  explained  for  adjacent  tones.  For,  if  we  represent 
the  vibration-amplitudes  of  a  certain  tone  symbolically  by 
the  ordinates  of  the  curve  abc.  Fig.  35,  and  imagine  this 
curve  gradually  moved  in  the  direction  of  the  arrow,  then, 
since  necessarily  several  organs  always  yield  simultaneous 
responses,  neighboring  tones  will  always  have  faint,  common 
excitations.  But  more  distant  tones  also  possess  a  certain 
similarity ;  and  even  between  the  highest  and  lowest  tones 

we  can  detect  a  resem- 
blance. Consequently,  in 
accordance  with  the  prin- 
ciple of  investigation  by 
which  we  are  guided,  we 
are  obliged  to  assume  in 
all  tone  -  sensations  com- 
**  mon  component  parts. 

Consequently,  there  can- 
not be  as  many  specific  energies  as  there  are  distinguishable 
tones.  For  the  understanding  of  the  facts  with  which  we 
are  here  concerned,  it  suffices  to  assume  only  two  energies, 
which  are  excited  in  different  proportions  by  different  rates  o* 
vibration.  Further  complexity  of  the  sensations  of  tone  is 
not  excluded  by  these  facts,  but  on  the  contrary  is  rendered 
probable  by  phenomena  to  be  discussed  later. 

Careful  psychological  analysis  of  the  tonal  series  leads 
immediately  to  this  view.  But  even  supposing  we  assume 
a  special  energy  for  every  end-organ,  and  reflect  that  these 
energies  are  similar  to  one  another,  that  is,  must  contain 
common  component  parts,  virtually  we  arrive  at  the  same 


THE  ANALYSIS  OF  SENSATIONS        277 

standpoint.  Let  us  therefore  assume,  merely  in  order  to 
have  a  definite  picture  before  us,  that,  in  the  transition 
from  the  lowest  to  the  highest  rates  of  vibration,  the 
tonal  sensation  varies  similarly  to  the  color-sensation 
in  passing  from  pure  red  to  pure  yellow,  say  by  the 
gradual  admixture  of  yellow.  We  can  fully  retain,  on 
this  view,  the  idea  that  there  is  for  every  distinguishable 
rate  of  vibration  a  special  appropriate  end-organ;  but 
in  that  case  not  absolutely  different  energies,  but 
always  the  same  two  energies,  only  in  different  propor- 
tions, are  disengaged  by  the  different  organs.1 


10. 

How  does  it  happen,  now,  that  so  many  tones  simul- 
taneously sounded  are  distinguished,  and  are  not  fused  into 
a  single  sensation  \  or  that  two  tones  of  different  pitch  do 
not  blend  to  a  mixed  tone  of  intermediate  pitch?  The 
fact  that  this  does  not  happen,  lends  a  still  more  definite 
shape  to  the  conception  which  we  have  to  form.  The  case 
is  probably  similar  to  that  of  a  graduated  series  of  mixed 
reds  and  yellows  situated  at  different  points  of  space,  which 
are  likewise  distinguished  and  do  not  blend.  And  in  fact, 
the  sensation  which  ensues  when  the  attention  passes  from 
one  tone  to  another  is  similar  to  that  which  accompanies 

1  The  view  that  different  end-organs  respond  to  different  rates  of 
vibration  is  too  well  supported  by  the  production  of  beats  by  neighbor- 
ing tones,  and  by  other  facts  adduced  by  Helmholtz,  and  is  too  valuable 
for  the  comprehension  of  the  phenomena,  to  be  again  relinquished. 
The  view  here  presented  utilizes  the  facts  disclosed,  notably  by  Hering, 
in  the  analysis  of  color-sensations. 


278        THE  ANALYSIS  OF  SENSATIONS 

the  wandering  of  the  fixation-point  in  the  field  of  vision. 
The  tonal  series  occurs  in  something  which  is  an  analogue 
of  space,  but  is  a  space  of  one  dimension  limited  in  both 
directions  and  exhibiting  no  symmetry  like  that,  for  instance, 
of  a  straight  line  running  from  right  to  left  in  a  direction 
perpendicular  to  the  median  plane.  It  more  resembles  a 
vertical  right  line,  or  one  running  from  the  front  to  the 
rear  in  the  median  plane.  But  while  colors  are  not  con- 
fined to  certain  points  in  space,  but  may  move  about, 
which  is  the  reason  we  so  easily  separate  space-sensations 
from  color-sensations,  the  case  is  different  with  tone- 
sensations.  A  particular  tone-sensation  can  occur  only 
at  a  particular  point  of  the  said  one-dimensional  space,  on 
which  the  attention  must  in  each  case  be  fixed  if  the  tone- 
sensation  in  question  is  to  be  distinctly  perceived.  We 
may  now  imagine  that  different  tone-sensations  have  their 
origin  in  different  parts  of  the  auditive  substance,  or  that, 
in  addition  to  the  two  energies  whose  ratio  determines  the 
timbre  of  high  and  deep  tones,  a  third  exists,  which  is 
similar  to  a  sensation  of  innervation,  and  which  comes  into 
play  in  the  fixation  of  tones.  Or  both  conditions  might 
occur  together.  At  present  it  may  be  regarded  as  neither 
possible  nor  necessary  to  come  to  a  conclusion  in  the 
matter. 

That  the  province  of  tone-sensation  offers  an  analogy  to 
space,  and  to  a  space  having  no  symmetry,  is  unconsciously 
expressed  in  language.  We  speak  of  high  tones  and  deep 
tones,  not  of  right  tones  and  left  tones,  although  our  musical 
instruments  suggest  the  latter  designation  as  a  very  natural 
one. 


THE  ANALYSIS  OF  SENSATIONS        279 


ii. 

In  one  of  my  earliest  publications1  I  supported  the 
view  that  the  fixation  of  tones  was  connected  with  a 
varying  tension  of  the  tensor  tympanL  I  am  now  unable 
to  maintain  this  view  in  the  light  of  subsequent  observa- 
tions and  experiments  which  I  have  made.  Nevertheless, 
the  space-analogy  does  not  fall  to  the  ground  for  this 
reason ;  only  the  appropriate  physiological  element  remains 
to  be  discovered.  The  supposition  that  the  processes  in 
the  larynx  during  singing  have  something  to  do  with  the 
formation  of  the  tonal  series  was  likewise  noticed  by  me 
in  my  work  of  1863,  but  I  did  not  find  it  tenable.  Singing 
is  connected  with  hearing  in  too  extrinsic  and  accidental 
a  manner.  I  can  hear  and  imagine  tones  far  beyond  the 

1  Zur  Theorie  des  Gehororgans,  1863.  By  means  of  experiments 
carried  out  by  me  in  co-operation  with  Kessel  ("  Ueber  die  Akkommo- 
dation  des  Ohres,"  Sitzungsberichte  der  Wiener  Akademie,  Vol.  LXVI., 
part  3,  October  1872),  I  obtained  a  proof  of  the  variable  disposition 
and  capacity  for  resonance  of  the  anterior  auditory  apparatus  in  the 
case  of  different  tones  ;  this  was  done  by  means  of  microscopic  observa- 
tion of  sound- vibrations  conducted  through  a  tube.  By  introducing  a 
tube,  and  making  our  observations  by  means  of  a  microscopic  ear- 
mirror  constructed  for  the  purpose,  we  tried  to  detect  a  similar  spon- 
taneous change  of  disposition  in  the  living  ear,  but  unsuccessfully.  I 
have,  however,  subsequently  been  inclined  to  doubt  whether  the 
powerful  vibrations  which  are  observed  in  this  way,  would  of  them- 
selves be  decisive  of  the  question,  since,  unless  they  were  muted,  they 
could  scarcely  penetrate  into  the  labyrinth  without  doing  damage. 
Consequently,  as  long  as  the  vibrations  cannot  be  observed  with 
certainty  in  a  normal  living  ear,  it  will  scarcely  be  possible  to  decide 
this  question  definitely.  A  method  of  light-interference  might  lead  to 
the  desired  result.  But  such  a  method  would  have  to  be  of  particularly 
simple  form,  if  it  is  to  be  applicable  under  the  difficult  conditions  of 
the  living  ear. 


280        THE  ANALYSIS  OF  SENSATIONS 

range  of  my  own  voice.  In  listening  to  an  orchestral 
performance  with  all  the  parts,  or  in  having  an  hallucination 
of  such  a  performance,  it  is  impossible  for  me  to  think 
that  my  understanding  of  this  broad  and  complicated  sound- 
fabric  has  been  effected  by  my  one  larynx,  which  is,  more- 
over, no  very  practised  singer.  I  consider  the  sensations 
which,  in  listening  to  singing,  are  doubtless  occasionally 
noticed  in  the  larynx,  a  matter  of  subsidiary  importance, 
like  the  pictures  of  the  keys  touched  which,  when  I  was 
more  in  practice,  sprang  up  immediately  into  my  imagina- 
tion on  hearing  a  performance  on  the  piano  or  organ. 
When  I  imagine  music,  I  always  distinctly  hear  the  notes. 
Music  can  no  more  come  into  being  merely  through  the 
motor  sensations  accompanying  musical  performances, 
than  a  deaf  man  can  hear  the  music  by  watching  the 
movements  of  players.  I  cannot  therefore,  agree  with 
Strieker  on  this  point.  (Cp.  Strieker,  Du  langage  et  de  la 
musique,  Paris,  1885). 

Different  is  my  opinion  with  regard  to  Strieker's  views  on 
language.  (Cp.  Strieker,  Die  Sprachvorstellungen,  Vienna, 
1880.)  It  is  true  that  in  my  own  case  words  of  which 
I  think  reverberate  loudly  in  my  ear.  Moreover,  I  have 
no  doubt  that  thoughts  may  be  directly  excited  by  the 
ringing  of  a  housebell,  by  the  whistle  of  a  locomotive,  etc., 
and  that  small  children  and  even  dogs  understand  words 
which  they  cannot  repeat.  Nevertheless,  I  have  been 
convinced  by  Strieker  that  the  ordinary  and  most  familiar, 
though  not  the  only  possible  way  by  which  speech  is 
comprehended,  is  really  motor,  and  that  we  should  be 
badly  off  if  we  were  without  it.  I  can  cite  corroborations 
of  this  view  from  my  own  experience.  I  frequently  see 


THE  ANALYSIS  OF  SENSATIONS        281 

strangers  who  are  endeavoring  to  follow  my  remarks 
slightly  moving  their  lips.  If  a  person  tells  me  his 
place  of  residence  and  I  omit  to  repeat  the  street 
and  number  of  the  house  after  him,  I  am  certain  to 
forget  the  address,  but  with  the  exercise  of  this 
precautionary  measure,  I  retain  it  perfectly  in  memory. 
A  friend  told  me  recently  that  he  would  not  read 
the  Indian  drama  Urvasi,  because  he  had  great  diffi- 
culty in  spelling  out  the  names,  and  consequently 
could  not  retain  them  in  memory.  The  dream  of 
the  deaf-mute,  which  Strieker  relates,  is  intelligible 
only  from  his  point  of  view.  In  fact,  on  calm 
reflexion  this  seemingly  paradoxical  relation  is  by  no 
means  so  remarkable.  The  extent  to  which  our  thoughts 
move  in  accustomed  and  routine  channels  is  shewn 
by  the  surprise  produced  by  witticisms.  Good  jokes 
would  be  more  frequent  if  our  minds  moved  less  in 
ruts.  To  many  the  obvious  collateral  meanings  of 
words  never  suggest  themselves.  Who,  for  example, 
in  using  the  names  Smith,  Baker,  or  Taylor  thinks  of 
the  occupations  designated  !  To  adduce  an  analogous 
example  from  a  different  field,  I  may  state  (cp.  p.  in) 
that  I  immediately  recognize  writing  reflected  in  a 
mirror  and  accompanying  its  original,  as  symmetrically 
congruent  with  the  latter,  although  I  am  not  able 
to  read  it  directly,  because  of  my  having  learned 
writing  by  motor  methods,  with  my  right  hand. 
I  can  also  best  illustrate  by  this  example  why  I  do  not 
agree  with  Strieker  in  regard  to  music :  music  is  related 
to  speech  as  ornament  is  to  writing. 


282        THE  ANALYSIS  OF  SENSATIONS 


12. 

I  have  repeatedly  illustrated  by  experiments,  which  I 
will  cite  again  here,  the  analogy  between  fixing  the  eyes 
on  points  in  space  and  fixing  the  attention  on  tones.  One 
and  the  same  combination  of  two  tones  sounds  different 
according  as  we  fix  our  attention  upon  the  one  or  the  other. 
Combinations  i  and  2  in  the  annexed  cut  have  a  perceptibly 
different  character  according  as  we  fix  our  attention  on  the 
higher  or  on  the  lower  note.  Persons  not  able  to  transfer 
their  attention  at  will  will  be  helped  by  having  one  note 


sounded  later  than  the  other  (3,  4).  The  one  sounded  last 
then  draws  the  attention  after  it.  With  a  little  practice  it 
is  possible  to  decompose  a  chord  (as,  for  instance,  5)  into 
its  elements  and  to  hear  the  constituent  tones  by  themselves 
(as  in  6).  These  and  the  following  experiments  are  better 
and  more  convincingly  carried  out  upon  a  physharmonica, 
on  which  the  notes  can  be  held,  than  on  a  piano. 

Especially  astonishing  is  the  phenomenon  produced  when 
.we  cause  one  note  of  a  chord,  on  which  the  attention  is 
fixed,  to  be  damped.  The  attention  then  passes  over  to 
one  of  the  notes  nearest  to  it,  which  comes  out  with  the 
distinctness  of  a  note  that  has  just  been  struck.  The 
impression  made  by  the  experiment  is  quite  similar  to  that 
which  we  receive  when,  absorbed  in  work,  we  suddenly 


THE  ANALYSIS  OF  SENSATIONS        283 

hear  the  regular  striking  of  the  clock  emerge  into  distinct- 
ness after  having  entirely  vanished  from  consciousness.  In 
the  latter  case  the  entire  tonal  effect  passes  the  threshold  of 
consciousness,  whilst  in  the  former  a  part  is  augmented.  If 
in  7,  for  example,  we  fix  the  attention  upon  the  upper  note, 


» 

s  — 

r      j~*7    ' 

Fl  —  H 

pi  —  H 

~P^ 

1 

4 

I 

A  — 

••'  X 

p  t  ^      ' 

letting  go,  successively  from  above,  the  keys  damping  the 
other  notes,  the  effect  obtained  is  approximately  that  of  8. 
If,  in  9,  we  fix  the  attention  on  the  lowest  note,  and  proceed 
in  the  reverse  order,  we  obtain  the  impression  represented 
in  10.  The  same  chordal  sequence  sounds  quite  different 
according  to  the  part  on  which  the  attention  is  fixed.  If, 
in  1  1  or  1  2,  I  fix  my  attention  on  the  upper  note,  the  timbre 


3 


12 


ry       »      *£    \\          „         i 

NHr-^-     ^^ 


alone  appears  to  be  altered.  But  if,  in  II,  the  attention  be 
fixed  upon  the  bass,  the  entire  acoustic  mass  will  seem  to 
sink  in  depth  ;  while  in  1 2  it  will  appear  to  rise  if  we  regard 
closely  the  succession  e-f.  This  makes  it  quite  evident,  in 
fine,  that  chords  act  the  part  of  clangs  (or  compound  notes 
embracing  both  fundamentals  and  harmonics).  The  facts 


284        THE  ANALYSIS  OF  SENSATIONS 

here  advanced  remind  us  strongly  of  the  changing  impres- 
sion received  when,  in  observing  an  ornamental  design,  the 
attention  is  alternately  fixed  on  different  points. 

We  may  also  recall  to  mind  here  the  involuntary  wander- 
ing of  the  attention  which  takes  place  during  the  continuous 
and  uniform  sounding  of  a  note  on  the  harmonium,  where 
if  the  note  lasts  several  minutes,  all  the  overtones  will  of 
themselves  successively  emerge  into  full  distinctness.1  The 
process  appears  to  point  to  a  sort  of  fatigue  for  the  note  on 
which  the  attention  has  long  been  fixed.  This  fatigue, 
moreover,  is  rendered  quite  probable  by  an  experiment 
which  I  have  described  at  length  in  another  place.2 

The  relations  in  the  sphere  of  tone-sensation,  which 
I  we  have  here  been  describing,  might  be 
illustrated  perhaps  more  palpably  by  some 
such  parallel  as  the  following.  Suppose 
that  our  two  eyes  were  capable  of  only  a 
single  movement,  and  that  they  could  only 
follow,  by  changing  motions  of  symmetrical 
convergence,  the  points  of  a  horizontal 
straight  line  lying  in  the  median  plane ;  and 
suppose  that  the  nearest  point  on  this  line 

Fig.  36. 

fixed  by  the  eyes  were  pure  red,  and  the 
point  farthest  away,  corresponding  to  the  position  of 
parallelism,  were  pure  yellow,  while  between  them  lay  all 
intermediate  shades  ;  then  the  system  of  sight-sensations 
so  constructed  would  quite  palpably  resemble  the  relations 
of  the  sensations  of  tone. 

1  Cp.  my  Einleitung  in  die  Helmholtzsche  Musiktheorie,  p.  29. 

2  Cp.  my  Grundlinien  der  Lehre  von  den  Bewegiingsempfindtingen^ 
p.  58. 


THE  ANALYSIS  OF  SENSATIONS        285 


On  the  view  hitherto  developed,  an  important  fact,  which 
we  shall  now  consider,  remains  unintelligible,  though  its 
explanation  is  absolutely  necessary  if  the  theory  is  to  lay 
any  claim  to  completeness.  If  two  series  of  tones  be  begun 
at  two  different  points  on  the  scale,  but  be  made  to  main- 
tain throughout  the  same  ratios  of  vibration,  we  recognize 
in  both  the  same  melody,  by  a  mere  act  of  sensation,  just 
as  readily  and  immediately  as  we  recognize  in  two  geome- 
trically similar  figures,  similarly  situated,  the  same  form. 
Like  melodies,  differently  situated  on  the  scale,  may  be 
termed  tonal  constructs  of  like  tonal  form,  or  they  may  be 
termed  similar  tonal  constructs.  It  is  easy  to  convince 
oneself  that  this  recognition  is  not  connected  exclusively 
with  the  employment  of  ordinary  musical  intervals  or  of  any 
comparatively  simple  ratio  of  vibration-numbers  in  common 
use.  If  the  open  strings  of  a  violin,  or  of  any  other  instru- 
ment with  more  than  one  string,  be  "tuned  to  any  discon- 
nected notes  we  please,  and  a  strip  of  paper,  divided  up 
into  any  complicated  series  of  ratios,  be  fastened  to  the 
finger-board,  we  can  play  the  notes  indicated  in  any  order 
(or  slide  from  one  to  the  other),  first  on  one  string  and 
then  on  the  others.  Now  although  the  resultant  sound 
may  have  no  sense  as  music,  we  can  recognize  the  melody 
as  the  same  on  each  string.  The  experiment  would  not 
be  any  more  convincing,  if  we  deliberately  divided  the 
finger-board  into  irrational  intervals.  Indeed  in  practice 
the  result  would  be  only  approximate.  The  musician  could 
still  maintain  that  he  heard  intervals  that  were  approximate 
or  intermediate  to  the  familiar  musical  intervals.  Untrained 


286        THE  ANALYSIS  OF  SENSATIONS 

song-birds  use  the  musical  intervals  only  in  exceptional 
cases. 

Even  in  a  series  of  only  two  tones,  the  sameness  of  the 
ratios  of  vibration  is  at  once  recognized.  Thus  in  the 
series  c-f,  d-g,  e-a,  etc.,  the  notes  which  have  all  the  same 
ratios  of  vibration  (3  : 4),  are  immediately  recognized  as 
like  intervals,  as  fourths.  Such  is  the  fact,  in  its  simplest 
form.  The  ability  to  pick  out  and  recognize  intervals  is 
the  first  thing  required  of  the  student  of  music  who  is 
desirous  of  becoming  thoroughly  familiar  with  his  subject. 

In  a  little  work,1  well  worth  reading,  by  E.  Kulke,  mention 
is  made,  bearing  on  this  point,  of  an  original  method  of 
instruction  by  P.  Cornelius — a  notice  which  I  will  now 
supplement  by  the  following  communication  made  to  me 
orally  by  Kulke  himself.  According  to  Cornelius,  it  is  a 
great  help  in  the  recognition  of  intervals  to  make  note  of 
particular  pieces  of  music,  folk-songs,  etc.,  which  begin 
with  these  intervals.  The  overture  to  TannMuser,  for 
example,  begins  with  a  fourth.  If  I  hear  a  fourth  I  at  once 
remark  that  the  tone-sequence  might  be  the  beginning  of 
the  overture  to  Tannhauser,  and  by  this  means  I  recognize 
the  interval.  In  like  manner,  the  overture  to  Fidelia 
(No.  i)  may  be  used  as  the  representative  of  the  third ;  and 
so  on.  This  excellent  device,  which  I  have  put  to  the  test 
in  my  lectures  on  acoustics  and  have  found  very  effective, 
apparently  complicates  matters.  One  would  naturally 
suppose  that  it  would  be  easier  to  make  note  of  an  interval 
than  of  a  melody.  Nevertheless,  a  melody  offers  a  greater 
hold  to  memory  than  does  an  interval,  just  as  an  individual 

1  E.  Kulke,  Ueber  die   Umbildung  der  Melodic.     Ein  Beitrag  zur 
Entwicklungslehre,  Prague,  Calve,  1884. 


THE  ANALYSIS  OF  SENSATIONS        287 

countenance  is  more  easily  remarked  and  associated  with  a 
name  than  is  a  certain  facial  angle  or  a  nose.  Every  one 
makes  note  of  faces  and  associates  with  them  names ;  but 
Leonardo  da  Vinci  arranged  noses  in  a  system. 


14. 

Just  as  every  interval  in  a  sequence  of  tones  is  made  per- 
ceptible in  a  characteristic  manner,  so  it  is  with  the  harmonic 
combinations  of  tones.  Every  third,  every  fourth,  every 
major  or  minor  triad  has  its  characteristic  color,  by  which  it 
is  recognized  independently  of  the  pitch  of  the  fundamental, 
and  independently  of  the  number  of  beats,  which  rapidly 
increases  with  increasing  pitch. 

A  tuning-fork  held  before  one  ear  is  very  feebly  heard  by 
the  other  ear.  If  two  slightly  discordant,  beating  tuning- 
forks  are  held  in  front  of  the  same  ear,  the  beats  are  very 
distinct.  But  if  one  of  the  forks  be  placed  before  one  ear, 
and  the  other  before  the  other,  the  beats  will  be  greatly 
weakened.  Two  forks  of  harmonic  interval  always  sound 
slightly  rougher  before  one  ear.  But  the  character  of  the 
harmony  is  preserved  when  one  is  placed  before  each  ear.1 
The  discord  also  remains  quite  perceptible  in  this  experi- 
ment. Harmony  and  discord  are,  however,  not  determined 
by  beats  alone. 

In  melodic  as  well  as  in  harmonic  combinations,  notes 
whose  rates  of  vibrations  bear  to  one  another  some  simple 
ratio,  are  distinguished  (i)  by  their  agreeableness,  and  (2) 
by  a  sensation  characteristic  of  this  ratio.  As  for  the 

1  Cp.  Fechner,  Ueber  einige  Verhtiltnisse  des  binocularen  Se/iens, 
Leipzig,  1860,  p.  536.  I  have  myself  often  tried  such  experiments. 


288        THE  ANALYSIS  OF  SENSATIONS 

agreeable  quality,  there  is  no  denying  that  this  is  partly 
explained  by  the  coincidence  of  the  overtones,  and,  in  the 
case  of  harmonic  combination,  by  the  consequent  efface- 
ment  of  the  beats,  resulting  always  where  the  ratios  of  the 
numbers  representing  the  vibrations  satisfy  certain  definite 
conditions.  But  the  experienced  and  unprejudiced  student 
of  music  is  not  entirely  satisfied  with  this  explanation.  He 
is  disturbed  by  the  preponderant  r61e  accorded  to  the 
accident  of  acoustic  color,  and  notices  that  tones  further 
stand  to  each  other  in  a  positive  relation  of  contrast,  like 
colors,  except  that,  in  the  case  of  colors,  no  such  definite 
agreeable  relations  can  be  specified. 


The  fact  that  a  sort  of  contrast  really  does  exist  among 
tones  almost  forces  itself  upon  our  notice.  A  smooth,  un- 
changing tone  is  something  very  unpleasing  and  colorless, 
like  a  single  uniform  color  enveloping  our  entire  surround- 
ings. A  lively  effect  is  produced  only  on  the  addition  of 
a  second  tone,  a  second  color.  In  like  manner,  if  we 
cause  a  tone  gradually  to  mount  in  pitch,  as  in  experiments 
with  the  siren,  all  contrast  is  lost.  Contrast  exists,  how- 
ever, between  tones  farther  apart,  and  not  merely  between 
those  immediately  following  one  another,  as  the  accompany- 
ing example  will  shew.  Passage  2  sounds  quite  different 
after  i  from  what  it  does  alone,  3  sounds  different 
from  2,  and  even  5  different  from  4  immediately 
following  3. 


THE  ANALYSIS  OF  SENSATIONS        289 

16. 

Let  us  turn  now  to  the  second  point,  the  characteristic 
sensation  corresponding  to  each  interval,  and  ask  if  this 
can  be  explained  on  our  present  theory.  If  a  fundamental 
n  be  melodically  or  harmonically  combined  with  its  third 
m,  the  fifth  harmonic  of  the  first  note  (5^)  will  coincide 

i 

C         c         g         c         e         g     b-flat     c 

n  zn  3«  4»  5*  6n  7*  8n 


e         b         e   g-sharp  b          d 

•zm          yn         qm          yn          6fft          jtn 


t      =      =      = 

F          f         c         f          a         c      e-flat      f 

n  2»  3«  4«  5»  ()«  7»  8» 

t       =       =       =       = 
A         a         e         a   c-sharp  e         g         a 

m  -im  yn          ^m  $m  bnt  -jm  8f» 

with  the  fourth  of  the  second  note  (40*).  This,  according 
to  the  theory  of  Helmholtz,  is  the  common  feature  char- 
acterizing all  third  combinations.  If  I  combine  the 
notes  Cand  E,  or  F  and  A,  representing  their  harmonics 
in  the  above  table,  then,  as  a  fact,  in  the  one  case  the 
harmonics  marked  ]  and  in  the  other  those  marked  j 
coincide ;  and  in  both  cases  the  coincidence  is  between 
the  fifth  harmonic  of  the  lower  and  the  fourth  harmonic  of 
the  higher  note.  Be  it  noted,  however,  that  this  common 
feature  exists  solely  for  the  understanding,  being  the  result 


2go        THE  ANALYSIS  OF  SENSATIONS 

of  a  purely  physical  and  intellectual  analysis,  and  has 
nothing  to  do  with  sensation.  For  sensation  the  real 
coincidence  in  the  first  case  is  between  the  e's,  and  in  the 
second  between  the  a's,  which  are  entirely  different  notes. 
On  the  assumption  that  there  exists  for  every  distinguish- 
able rate  of  vibration  an  appropriate  specific  energy,  we 
are  obliged,  more  than  on  any  other  theory,  to  ask  where 
is  the  common  component  of  sensation  hidden  that 
characterizes  every  third  combination  ? 

I  must  insist  on  this  distinction  of  mine  not  being  re- 
garded as  a  piece  of  pedantic  hair-splitting.  I  propounded 
the  question  involving  it  about  twenty  years  ago,  at  the  same 
time  with  my  question  as  to  wherein  physiological  similarity 
of  form,  as  distinguished  from  geometrical,  consisted ;  and 
the  former  is  not  a  whit  more  unnecessary  than  was  the  latter, 
of  which  the  superfluity,  too,  in  the  issue,  was  disproved.  If 
we  are  to  allow  a  physical  or  mathematical  characteristic  of 
the  tierce-interval  to  stand  as  a  mark  of  the  tierce-sensation, 
then  we  should  content  ourselves,  as  Euler  did,1  with  the 
coincidence  of  every  fourth  and  fifth  vibration — a  concep- 
tion which  was,  after  all,  not  so  bad,  as  long  as  it  could  be 
believed  that  sound  continued  its  course  in  the  nerve-tracts, 
also,  as  periodic  motion,  a  view  which  even  A.  Seebeck2 

1  Euler,  Tentamen  novce  theories  musicce^  Petropoli,  1739,  p.  36. 

2  I  cannot  understand  how  any  one  can  still  maintain  the  theory  of 
the  temporal  coincidence  of  impulses.     At   one  time  I   replaced  A. 
Seebeck's  experiment   by  what   I   believe   to  be  a  better  procedure 
("  Ueber  einige  der  physiologischen  Akustik  angehorige  Erscheinun- 
gen,"  Berichte  der  Wiener  Akademie,  26th  June  1864),  but  I  never  could 
detect  any  periodicity  in  the  nerve-process  connected  with  sensation. 
At  that  time  it  was  not  known  that  beats  are  never  observed  between 
a  subjective  tone  and  an  adjacent  objective  tone,  or  between  subjective 
ones  ;  but  the  fact  cannot  now  be  doubted.     Cp.  Stumpf's  interesting 


THE  ANALYSIS  OF  SENSATIONS        291 

(Pogg.  Ann.,  Vol.  LXVIII.)  regarded  as  possible.  With 
regard  to  this  particular  point,  Helmholtz's  coincidence  of 
5«  and  $m  is  in  no  respect  less  symbolical  and  does  not 
offer  greater  enlightenment. 


So  far  I  have  presented  my  arguments  with  the  convic- 
tion that  I  should  not  find  it  necessary  to  make  a  single 
retrograde  step  of  importance.  This  feeling  does  not  accom- 
pany me  in  the  same  measure  in  the  development  of  the 
following  hypothesis,  which,  in  all  its  essential  features, 
was  suggested  to  me  a  long  time  ago.  Yet  the  hypothesis 
may  at  least  serve  to  clear  up  and  illustrate,  from  the 
positive  side  also,  the  requirement  which  I  believe  a  more 
complete  theory  of  tone-sensations  is  bound  to  meet.  I 
will  first  expound  my  view  in  the  form  in  which  it  appeared 
in  the  first  edition  of  this  book. 

Let  us  suppose  that  it  is  an  extremely  important  vital 
condition  for  an  animal  of  simple  organization  to  perceive 
slight  periodic  motions  of  the  medium  in  which  it  lives. 
If  (owing  to  the  relatively  excessive  size  of  its  organs,  and 
its  consequent  lack  of  receptivity  for  such  rapid  changes) 

paper  on  "  Beobachtungen  liber  subjective  Tone  und  tiber  Doppelt- 
horen  "  (Zeitschrift  fur  Psychologic  und  Physiologic  der  Sinnesorgane, 
Vol.  XXL,  pp.  100-121).  The  subjective  tones  that  arise  in  my  ear 
generally  last  too  short  a  time  for  me  to  experiment  with  them.  Still 
I  did  succeed  not  long  ago  (1906)  in  getting  to  the  piano  with  a  very 
clear  and  constant  c-sharp,  and  convincing  myself  that  when  a  c-sharp 
a  shade  deeper  was  lightly  struck  on  the  piano,  no  beats  were  demon- 
strable. For  me,  indeed,  this  demonstration  was  superfluous,  for  I 
hold  the  opposite  supposition  to  be  physiologically  inadmissible.  But 
Stumpf  s  observations  on  the  consonance  and  dissonance  of  subjective 
tones  without  beats  are  very  important. 


292        THE  ANALYSIS  OF  SENSATIONS 

change  of  attention  is  too  sluggish,  and  the  period  of  the 
oscillations  is  too  short,  or  their  amplitude  too  small,  to 
permit  the  single  phases  of  the  excitation  to  enter  con- 
sciousness, it  may  nevertheless  be  possible  under  certain 
conditions  for  the  animal  to  perceive  the  accumulated  sensa- 
tion-effects of  the  oscillatory  stimulus.  The  organ  of  hear- 
ing will  outstrip  the  organ  of  touch.1  Now  an  end-organ 
capable  of  vibration  (say  an  auditory  cilium)  responds,  by 
virtue  of  its  physical  qualities,  not  to  every  rate  of  vibration, 
nor  to  one  only,  but  ordinarily  to  several,  at  a  considerable 
distance  apart.2  Therefore,  as  soon  as  the  whole  continuum 
of  rates  of  vibration  between  certain  limits  becomes  of 
importance  for  the  animal,  a  small  number  of  end  organs 
no  longer  suffices,  but  the  need  of  a  whole  series  of  such 
organs  of  graduated  capacity  arises.  At  first  the  organ  of 
Corti  and  the  basilar  membrane  were  regarded  by  Helmholtz 
as  such  a  system. 

It  can  hardly  be  expected,  however,  that  a  member  of 
such  a  system  will  respond  to  only  one  rate  of  vibration. 
On  the  contrary,  we  should  expect  that  it  would  respond 
with  enfeebled  but  graduated  intensity  (perhaps  from  being 
divided  by  nodes)  to  the  rates  of  vibration  2n,  3^,  4«,  etc., 
as  also'^to  the  rates  of  vibration  «/2,  «/3,  «/4,  etc.  Inasmuch 

1  It  is  questionable  therefore  whether  animals  which  have  so  small  a 
measure  of  time  that  their  voluntary  movements  produce  a  musical  note 
hear  in  the   ordinary  sense,  or  whether  with   them   it   is  not    rather 
touch  which  makes  on  us  the  impression  of  hearing.     Cp.,  for  example, 
the   admirable   experiments   and   observations   of  V.    Graber   ("  Die 
Chordotonalen  Organe,"  Arch,  fur  Microskop.  Anat.,  XX.,  p.  506). 
— Cp.  also  my  Beuoegungsempfindungen,  p.  123.     This  conjecture  has 
subsequently   been   confirmed  in   many   ways.     See   Pop-ii lar-wis sen- 
se haft  liche  Vorlesitngen,  3rd  ed.,  p.  401. 

2  As  V.  Hensen,  for  example,  has  observed. 


THE  ANALYSIS  OF  SENSATIONS        293 

as  the  assumption  of  a  special  energy  for  each  rate  of 
vibration  has  proved  untenable,  we  may  imagine,  agreeably 
to  what  has  been  said  above,  that  in  the  first  place,  only  two 
sensation-energies,  say,  Dull  (D)  and  Clear  (C),  are  excited. 
The  resultant  sensation  we  will  represent  symbolically 
(somewhat  as  we  do  in  mixed  colors)  by  pD  +  qC ;  or, 
making /  +  ^  =  i  and  regarding  q  as  a  function  f(n)  of  the 
rate  of  vibration,1  by  [T  -f(n)}  D+f(n)  C.  The  sensation 
arising  will  now  correspond  to  the  number  of  the  vibrations 
of  the  oscillatory  stimulus,  to  whatever  member  of  the  series 
of  end-organs  the  stimulus  may  be  applied.  And  con- 
sequently our  earlier  view  will  not  be  materially  disturbed 
by  the  new  hypothesis.  For,  since  the  member  £n  responds 
most  powerfully  to  n,  and  only  in  a  much  more  enfeebled 
degree  to  2#,  $n,  or  to  n/2,  n/$,  Rn  vibrating  with  n  even 
in  case  of  an  aperiodic  impulse,  therefore  the  sensation 
[i  -/(«)]  D+f(n)  C  will  still  be  predominantly  associated 
with  £„ . 

Well-attested  cases  of  double  hearing  (cp.  Stumpf,  loc. 
tit.,  p.  266  et  seq.)  point  forcibly  to  the  conclusion  that 
the  ratios  in  which  D  and  C  are  disengaged  are  dependent 
upon  the  end-organ,  and  not  upon  the  rate  of  vibration — 
a  conclusion  which  would  also  not  affect  our  theory. 

A  member  Rn,  accordingly,  responds  powerfully  to  #, 
and  also,  though  more  weakly,  to  2«,  3^,  ....  n/2, 
n/3  ....  with  the  sensations  belonging  to  these  rates  of 
vibration.  It  is,  however,  extremely  improbable  that  exactly 
the  same  sensation  is  excited  whether  Rn  responds  to  n,  or 
whether  Rn  responds  to  «.  On  the  contrary,  it  is  probable 
that  every  time  the  members  of  the  series  of  organs  respond 
1  Thus,  to  take  a  very  simple  example,  we  might  make  /(«)  — k.  log.  «. 


294        THE  ANALYSIS  OF  SENSATIONS 

to  a  partial  tone,  the  sensation  receives  a  weak  supple- 
mentary coloring,  which  we  will  represent  symbolically,  for 
the  fundamental  tone  by  Z1?  for  the  overtones  by  Z2,  Z3, 
.  .  .  .,  and  for  the  undertones  by  Z^  Zi,  .  .  .  .  On  this 
supposition,  sensations  of  tone  would  be  somewhat  richer  in 
composition  than  would  follow  from  the  formula  [i  -f(n)]  D 
+f(n)  £•  The  sensations  which  the  series  of  end-organs, 
as  excited  by  the  fundamentals,  yields,  constitute  a  province 
with  the  supplementary  coloring  Zv  the  excitation  of  the 
same  series  by  the  first  overtone  yields  a  special  province 
of  sensation  with  the  supplementary  coloring  Z2,  etc.  The 
Z's  may  be  either  unchanging  elements,  or  may  themselves, 
again,  consist  of  two  components,  U  and  F,  and  form  series 
representable  by  [i  -/(«)]  U+f(n)  F.  But  at  present  the 
decision  on  this  last  point  is  immaterial. 

It  is  true  that  the  physiological  elements  Z15  Z2,  .  .  .  . 
have  yet  to  be  found.  Yet  the  very  perception  that  they 
have  to  be  sought  seems  to  me  of  importance.  Let  us  see 
what  form  the  province  of  tone-sensations  would  take  on 
if  we  regarded  Zj,  Z2,  ....  as  given. 

We  will  take  as  example  a  melodic  or  harmonic  major- 
third  combination,  whose  rates  of  vibration  are  n  =  ^p 
and  m  =  $p;  the  lowest  of  the  overtones  common  to  the 
two  is  5«  =  4m  =  20^,  the  highest  of  the  undertones  common 
to  the  two  is  p.  Then  we  obtain  the  table  on  the 
following  page. 

Thus  in  the  third  combination,  the  supplementary  sensa- 
tions Z4,  Z5,  and  Z^  Zi,  which  are  characteristic  of  the 
third,  make  their  appearance  even  when  the  notes  contain 
no  overtones,  while  the  former  (Z4,  Z5)  are  strengthened 
when,  either  in  the  open  air  or  at  least  in  the  ear,  over- 


THE  ANALYSIS  OF  SENSATIONS        295 

tones  do  occur.     The  diagram  may  be  easily  generalized 
to  include  any  interval.1 

These  supplementary  colorings,  though  scarcely  notice- 
able in  single  tones,  or  in  running  continuously  through 
the  scale,  will  accordingly  become  conspicuous  in  combina- 
tions of  tones  having  certain  ratios  of  rate  of  vibration, 


The     members     of 

the  series  of  end- 

RP 

R$p 

R$p 

Rzop 

organs  : 

-a  c 

S| 

respond  to  the  rates 
of  vibration  ; 

4A5/ 

4* 

5/ 

*a* 

1L 

4 

SS-5  4 

•M 

with     the     supple- 

d      w 

mentary      sensa- 

Zi, Z& 

z\ 

zl 

Z!,Z, 

|-S 

tions  : 

*i 

they    also    respond 

g  ° 

to  the  rates  of  vi- 

20/> ~5(4/) 

20/»  =  4(5^) 

§| 

bration  : 

*^rf 

with     the     supple- 

g"« S 

mentary       sensa- 

^5 

Zi 

gS, 

tions  ; 

just  as  the  contrasts  of  faintly  colored,  almost  white  lights 
become  vivid  when  such  lights  are  brought  together.     And, 

1  The  above  exposition  will  be  found  in  a  rather  conciser  and  slightly 
different  form  in  my  note  "Zur  Analyse  der  Tonempfindungen " 
(Sitzungsberichte  der  Wiener  Akademie,  December  1885),  where  I 
have  tried  to  analyse  sensations  of  tone  on  the  analogy  of  sensations 
of  color,  of  which  the  analysis  has  been  carried  very  much  further. 
Every  vibration-number  disengages  a  few  specific  energies  in  a  ratio 
which  depends  on  the  vibration-number  in  question,  The  excitability 
of  these  energies  is  different  at  different  points  on  the  retina.  Analogous 
relations  are  assumed  mutatis  imitandis  for  sensations  of  tone.  It 


296        THE  ANALYSIS  OF  SENSATIONS 

furthermore,  the  same  contrast-colorings  always  correspond 
to  the  same  ratios  of  rate  of  vibration,  no  matter  what  the 
pitch. 

In  this  manner  it  is  intelligible  how  tones  may  receive, 
by  melodic  and  harmonic  combination  with  others,  the 
most  varied  colorings,  which  are  wanting  to  them  when 
singly  sounded. 

The  elements  Zlt  Z2  .  .  .  must  not  be  conceived  as 
unvarying  and  fixed  in  number.  On  the  contrary,  it  is 
to  be  supposed  that  the  number  of  perceptible  Z's  depends 
on  the  organization,  on  the  training  of  the  ear,  and  on  the" 
attention.  According  to  this  conception,  the  ear  does  not 
directly  cognize  ratios  of  rate  of  vibration  but  only  the 
supplementary  colorings  conditioned  by  these  ratios.  The 
tonal  series  symbolically  represented  by  [i  -f(n)]D  +f(n}  C 
is  not  infinite  but  limited.  Since  /  (n)  may  vary  between 
the  values  o  and  i,  D  and  C,  where  they  are  the  sensations 
corresponding  to  the  lowest  and  highest  tones,  are  the 
end-terms  of  the  series.  If  the  number  of  vibrations 
sinks  considerably  below  or  rises  considerably  above  that 
of  the  fundamental  of  the  extreme  term  of  the  series,  a 
weak  response  only  will  take  place,  but  no  alteration  of 
the  quality  of  the  sensation.  Further,  the  sensation  of 
the  intervals  must  disappear  in  the  neighborhood  of  the 

seemed  originally  that  in  both  cases  there  must  be  an  infinite  variety 
of  sensations  corresponding  to  the  infinite  variety  of  the  physical 
stimulus.  But  in  both  cases  psychological  analysis  leads  to  the  con- 
clusion that  a  smaller  number  of  sensations  is  to  be  assumed,  and  that, 
on  the  principle  of  parallelism,  we  have  to  think  of  these  sensations, 
not  as  immediately  dependent  on  the  complicated  physical  stimulus, 
but  as  immediately  dependent  on  the  psycho-physical  process  which  is 
as  simple  as  they  are  themselves. 


THE  ANALYSIS  OF  SENSATIONS        297 

two  limits  of  hearing ;  first,  because,  in  general,  differences 
between  sensations  of  tone  cease  at  this  point,  and,  secondly, 
because  at  the  upper  limit  the  members  of  the  series 
capable  of  being  excited  by  the  undertones  are  lacking, 
while  at  the  lower  limit  those  which  react  on  the  overtones 
are  lacking. 

Passing  in  review  again  the  position  at  which  we  have 
arrived,  we  see  that  with  few  exceptions  the  conclusions 
reached  by  Helmholtz  may  be  all  retained.  Noises  and 
composite  sounds  may  be  decomposed  into  musical  tones. 
To  every  distinguishable  rate  of  vibration  there  corre- 
sponds a  particular  nervous  end-organ.  In  place  of  the 
numerous  specific  energies  required  by  this  theory,  how- 
ever, we  substitute  two  only,  which  render  the  relationship 
of  all  tonal  sensations  intelligible,  and  which,  by  the  role 
which  we  assign  to  the  attention,  likewise  enable  us  to 
keep  perceptually  distinct,  several  tones  when  sounded 
together.  By  the  hypothesis  of  the  multiple  response  of 
the  members  of  the  series  of  end-organs,  and  by  that  of 
supplementary  acoustic  colorings,  the  significance  of 
accidental  acoustic  color  is  diminished,  and  we  get  a 
glimpse  of  the  direction  in  which,  notably  on  the  ground 
of  musical  facts,  the  positive  characteristics  of  intervals 
are  to  be  further  investigated.  Finally,  the  latter  con- 
ception supplies  Von  Oettingen's  principle  of  duality 
with  a  foundation  which  might  perhaps  commend 
itself  to  this  investigator  himself  as  preferable  to  his 
assumption  of  "memory";  while  at  the  same  time  it 
becomes  manifest  why  the  duality  cannot  be  a  perfect 
symmetry. 


298        THE  ANALYSIS  OF  SENSATIONS 

18. 

I  have  expressly  described  the  theory  of  the  multiple 
response  of  the  series  of  end-organs,  as  well  as  the  theory 
of  supplementary  colorings,  as  a  "hypothesis,"  and  I  have 
put  forward  this  hypothesis  merely  with  the  object  of 
illustrating  the  meaning  of  the  postulates  resulting  from 
psychological  analysis,  and  of  perhaps  stimulating  others 
to  a  more  successful  attack  on  the  problem.  I  am  there- 
fore not  surprised  to  find  that  other  writers  do  not  agree 
unreservedly  with  my  attempt.  But  that  this  hypothesis  is, 
as  Stumpf  says,1  useless  and  quite  unsuited  to  its  purpose, 
I  cannot  admit.  The  coincidence  of  the  supplementary 
colorings  Z4,  Z5,  or  Z±t  Zj,  in  one  and  the  same  nerve,  is 
not  merely  a  physical,  but  also  a  psycho-physical  fact.  It 
can  scarcely  be  a  matter  of  indifference  that  the  sensation 
of  a  mixed  coloring  is  determined  by  a  single  element.  On 
the  contrary,  it  seems  to  me  that  what  I  am  looking  for, 
namely  an  explanation  of  the  definite  coloring  of  the 
intervals, — and  also  what  Stumpf  is  looking  for, — namely 
an  explanation  of  fusion, — would  actually  be  represented 
by  the  partial  coincidence  which  I  assume,  even  without 
overtones.  -  Stumpf  s  further  assertion  that,  in  the  case  of 
notes  with  overtones,  there  is  no  difficulty  in  understanding, 
on  Helmholtz's  theory,  the  similarity  of  like  intervals,  rests 
upon  a  misapprehension  of  my  criticism  of  Helmholtz. 
It  will  satisfy  no  one  to  be  told  that  overtones  of  equal 
strength  coincide  in  the  case  of  two  tierces,  since  what  is 
in  question  is  the  qualitative  similarity  of  the  sensations. 

1C.  Stumpf,  Beitrage  z^^r  Akustik  imd  Musikwissenschaft^  Heft  I, 
pp.  17,  18. 


THE  ANALYSIS  OF  SENSATIONS        299 

If  the  recognition  of  a  melodic  tierce-interval  were  imme- 
diately intelligible,  it  would  of  course  be  unnecessary  to 
look  for  any  special  explanation  of  why  we  recognize  the 
harmonic  combination  of  tierces.  But  inasmuch  as  Stumpf 
himself  holds  that  the  melodic  steps  are  characterized  by 
the  harmonic  combination,  this  view  would  involve  a  vicious 
circle.  On  my  theory  also,  the  fact  of  melodic  and  harmonic 
selection  of  definite  ratios  of  vibration-numbers  leads  to  the 
same  problem.  My  hypothesis  inclines  towards  the  theory 
of  resonance,  and  according  to  Stumpf  is  to  be  rejected 
on  that  very  account.  I  will  presently  deal  more  particu- 
larly with  this  last  point. 

19. 

There  has  been  much  discussion  of  the  physical  pro- 
cesses involved  in  audition,  and,  in  particular,  of  the 
function  of  the  parts  of  the  middle  ear.  In  spite  of  this, 
it  would  seem  that  an  unprejudiced  revision  of  the  physical 
theory  of  audition  is  urgently  needed.  The  question  has 
been  raised  whether  the  auditory  ossicles  vibrate  as  a 
whole,  or  whether  the  sound-waves  pass  through  them. 
E.  H.  Weber  decides  in  favor  of  the  former  view,  which 
has  been  experimentally  confirmed  by  Politzer,  while  I 
was  probably  the  first  to  establish  it  on  a  theoretical  basis.1 
For  if  the  dimensions  of  the  ossicles  in  comparison  with 
the  length  of  the  sound-waves  in  question  are,  as  regards 
their  material,  very  small  (as  is  actually  the  case),  there 
can  be  no  doubt  that  practically  the  same  phases  of  move- 

1  Mach,  "  Zur  Theorie  des  Gehororgans,"  Sitzungsberichte  der  Wiener 
Akademie,  Vol.  LVIIL,  July  1863.  Also  Helmholtz,  Die  Mechanik 
der  Gehorknochelchen,  1869. 


300        THE  ANALYSIS  OF  SENSATIONS 

ment  occur  throughout  the  whole  extent  of  the  ossicles, 
and  that  consequently  they  must  move  as  a  whole.  It 
has  occurred  to  some  inquirers  to  transfer  the  movements 
of  the  ossicles  to  the  fluid  of  the  labyrinth.  But  patho- 
logical investigations  teach  us  that,  even  without  the 
co-operation  of  the  ossicles  and  the  membrana  tympani, 
the  hearing  may  remain  quite  good,  provided  that  the 
labyrinth  is  in  order.  The  ossicles  and  tympanum  seem 
only  to  be  important  when  what  is  in  question  is  the  trans- 
ference to  the  labyrinth  of  very  faint  movements  of  the 
air ;  in  that  case  the  reduction  of  the  pressure  falling  upon 
the  whole  surface  of  the  membrana  tympani  to  the  small 
stirrup-footplate  seems  to  be  necessary.  Otherwise,  sound- 
waves can  be  carried  to  the  labyrinth  by  way  of  the  cranial 
bones  also.  If  sounding  bodies,  such  as  tuning-forks,  are 
placed  on  different  parts  of  the  head,  it  can  be  shewn  that 
the  direction  of  the  sound-waves  that  penetrate  into  the 
labyrinth  does  not  play  any  important  part.  Again,  all 
dimensions  of  the  sound-perceiving  apparatus  are  so  small 
in  comparison  with  the  audible  soundwaves,  and  the 
velocity  of  sound  in  the  bones  and  the  labyrinthine  fluid 
is  so  great,  that  the  whole  extent  of  the  labyrinth  only 
contains  room  for  one  perceptible  wave-phase  at  any  one 
moment.  The  result  of  all  this  is,  that  it  is  not  the  move- 
ments and  the  direction  of  movement,  but  the  variations 
of  pressure  which  arise  in  the  labyrinth  almost  synchron- 
ously, that  are  to  be  regarded  as  the  decisive  stimulus  that 
excites  sensation. 

Nevertheless  let  us  consider  the  movement  which  can  be 
set  up  in  the  labyrinth  by  the  movements  of  the  stirrup- 
plate.  We  may  first  imagine  all  the  soft  parts  to  be  taken 


THE  ANALYSIS  OF  SENSATIONS        301 

out,  and  the  whole  space  bounded  by  the  osseous  wall  to 
contain  nothing  but  fluid.  The  movement  that  can  find 
room  here  is  a  periodical  current  passing  from  the  oval  to 
the  round  window  and  vice  versa,  the  form  of  which,  since 
the  velocity  of  the  disturbance  vanishes  in  proportion  to  the 
velocity  of  the  sound,  will  be  almost  entirely  independent 
of  the  period.  If  the  surfaces  of  the  two  windows  are  con- 
ceived as  positive  and  negative  electrodes,  and  as  conducting 
the  fluid,  then  the  lines  of  the  electric  current  will  coincide 
with  the  lines  of  the  periodic  current.  Now  this  state  of 
things  will  not  suffer  any  substantial  change,  if  the  difference 
between  the  specific  weight  of  the  soft  parts  and  that  of  the 
fluid  in  which  they  are  immersed  is  very  small.  It  is  the 
mass  of  the  fluid  that  is  of  predominant  importance.  The 
fact  that  particular  constructions  can',  according  to  the  pitch, 
take  on  a  special  local  state  of  vibration  in  spite  of  the  fluid, 
need  scarcely  be  discussed.  The  quantitative  relations  are 
here  quite  different  from  what  they  are  in  the  case  of  strings 
or  membranes  in  air. 

Consequently,  Ewald's  new  theory  of  audition 1  is,  in  my 
opinion,  no  more  tenable  than  the  theory  of  Helmholtz  as 
to  the  fibres  of  Corti  and  the  elective  vibrations  of  the 
basilar  membrane.  If  in  Ewald's  experiments  a  membrane 
coated  with  oil  shews,  when  the  coat  is  comparatively  thick, 
no  clear  divisions  any  longer,  it  would  completely  fail  to 
shew  any  if  it  were  immersed  in  a  fluid,  much  more  if  the 
dimensions  were  proportionately  reduced.  We  must,  how- 
ever, insist  that  Ewald's  theory  is  otherwise  appropriate  in 
many  respects,  and  that  it  would  offer  many  advantages. 
For  instance,  in  the  case  of  harmonic  intervals,  even  when 
1  Ewald,  Eine  neue  Hortheorie^  Bonn,  1899. 


302        THE  ANALYSIS  OF  SENSATIONS 

overtones  are  absent,  the  membranes  display  coincidences 
of  the  node-lines.  Thus  this  theory  seems  to  fulfil  a  part 
of  the  above  mentioned  postulates.  Unfortunately  it  is 
physically  inadmissible,  quite  apart  from  further  difficulties 
which  it  is  also  unable  to  solve.  I  need  scarcely  say  that  I 
do  not  presume  to  dismiss  so  admirable  and  laborious  a 
piece  of  work  in  a  few  words,  but  at  the  same  time  I  cannot 
refrain  from  stating  my  objections  to  it. 

Shortly  after  the  publication  of  the  fourth  edition  of  this 
book,  which  contained  the  foregoing  passages  expressing  my 
doubts  as  to  the  vibration  of  membranes  in  fluids,  Ewald 
published  his  experiments  with  the  camera  acustica.1  He 
immersed  in  water  a  delicate  membrane,  of  about  the 
dimensions  of  the  basilar  membrane,  and  succeeded  in 
acoustically  setting  up  in  it  continuous  vibrations  with  clear 
nodal  divisions  corresponding  to  the  pitch.  This  shewed 
that  my  conjecture  was  wrong,  and  gave  me  cause  to  reflect 
in  what  point  I  had  been  mistaken.  I  then  remembered 
the  very  small  nodal  divisions  which,  years  before,  I  had 
myself  observed  in  fluid  membranes.2  I  also  recalled 
Friesach's  experiments  with  strings  immersed  in  water,3  the 
result  of  which  had  been  to  shew  that  immersion  in  water 
acts  as  an  enlargement  of  the  string's  mass,  since  the  fluid 
in  the  immediate  neighborhood  of  the  string  accompanies 
its  vibrations,  moving  synchronously  to  and  fro  in  extremely 
short  paths.  It  is  therefore  quite  conceivable  that  the 
labyrinthine  fluid  vibrates  to  and  fro  as  a  whole,  and  that 

1  Ewald,  Pfliiger's  Archiv,  1903,  Vol.  XCIII.,  p.  485. 

2  Optisch-akustische  Versuche,  Prague,  1872,  p.  93, 

3  Friesach,  Berichte  der  Wiener  Akademie^  1867,  Vol.   LVL,  2nd 
part,  p.  316. 


THE  ANALYSIS  OF  SENSATIONS        303 

nevertheless  the  velocity  of  propagation  in  the  membrane, 
which  is  very  much  smaller,  appears  in  the  labyrinthine 
fluid  in  the  form  of  stable  vibrations  of  the  membrane.  If 
the  existence  of  such  vibrations  of  the  membrane  is  proved, 
Ewald's  theories  gain  greatly  in  value.  I  should  like, 
further,  to  refer  here  to  two  papers  by  Stohr  which  seem  to 
me  to  contain  the  germs  of  ideas  which  would  repay 
development.1 

20. 

The  difficulty  of  setting  the  theory  of  resonance  on  a 
sound  physical  basis  has  probably,  as  it  seems  to  me,  been 
felt  by  everyone  who  has  studied  it,  and  not  least  acutely 
by  its  originators.  But  at  the  same  time  it  was  recognized 
that,  if  it  was  given  up,  the  key  to  the  problem  of  the 
analysis  of  sounds  and  to  a  clear  and  simple  doctrine  of 
tone-sensations  would  be  lost.  Hence  the  frantic  attempts 
to  save  the  theory  of  resonance.  L.  Hermann  2  seems  to 
me  to  speak  very  much  to  the  point,  when  he  says  that 
we  cannot  do  without  some  sort  of  theory  of  resonance,  but 
that  this  need  not  necessarily  be  a  physical  theory,  but  may 
also  be  a  physiological  theory.  We  may  make,  with  him, 
the  plausible  assumption  that  the  nervous  organs  per  se 

1  Stohr,  "  Ueber  Unterbrechungstone,"  Deutsche  Revile,  July,  1904. 
Mach  and  Kessel  some  time  ago  pointed  out  the  necessity  of  attacking 
the  problems  of  acoustics  from  the  point  of  view  of  asymmetry ;  see 
"Die  Funktion  der  Trommelhohle,"  Berichte  der  Wiener  Akademie, 
Vol.  LXVI.,    3rd  part,   1872;  Stohr,  "  Klangfarbe  oder  Tonfarbe," 
SUdde^^tsche  Monalshefte,   Munich  and   Leipzig,  July  1904.      In  this 
paper  Stohr  is  aiming,  though  by  a  different  route,  at  a  goal  not  far 
removed  from  my  own. 

2  Hermann,  Pfliiger's  Archiv,  Vol.  LVL,  pp.  494  sqq.,  1894. 


304        THE  ANALYSIS  OF  SENSATIONS 

are  peculiarly  sensitive  to  stimuli  with  a  definite  period.1 
It  cannot  exactly  be  elastic  forces  that  impel  the  organ 
back  to  its  position  of  equilibrium,  but  we  may  think  of  a 
state  of  equilibrium  which  is  of  an  electrical  or  chemical 
nature,  the  deviations  from  it  standing  to  one  another  in 
the  relation  of  the  positive  to  the  negative  sign.  And 
further,  there  may  be  a  connexion  between  these  organs, 
by  means  of  which  one  can  act  as  a  stimulus  upon  another. 
In  this  way  a  reasonable  prospect  seems  to  be  opened  up 
of  making  up  for  the  loss  of  the  physical  theory.  I  cannot 
here  attempt  to  reproduce  Hermann's  arguments  com- 
pletely and  accurately,  but  must  content  myself  with 
referring  the  reader  to  his  paper. 

One  point,  however,  we  may  consider  more  closely. 
When  two  wave-shaped  pendular  vibrations  with  vibration- 
numbers  «,  «',  co-operate,  there  then  arise  beats  which 
may  be  regarded  as  a  rising  and  sinking  of  the  tone,  n  or 
n'  (n'  —  ri)  times  a  second.  But  it  is  never  possible  to 
regard  the  movement  of  the  air  as  such  a  movement  as 
could  contain  the  wave-vibration, — that  is  to  say,  the  tone 
n'  -  n.  Fven  a  physical  resonator  with  the  vibration- 
number  n'  -  n  can  never  be  excited  by  such  beats,  whether 
they  are  fast  or  slow.  Indeed,  it  is  easy  to  see,  when  one 
imagines  or  draws  the  course  of  the  beats,  that  in  the  long 
run  precisely  as  many  and  as  strong  positive  and  negative 
impulses  must  take  place  as  there  are  vibrations  (#'  -  n)  of 
the  resonator.  In  the  first  half  of  the  time,  also,  the 
impulses  are  equal  to  and  of  the  same  direction  as  the 

1  Perhaps  this  assumption  would  still  remain  valuable  if  it  also  suc- 
ceeded in  providing  a  basis  for  a  satisfactory  physical  theory  of 
resonance. 


THE  ANALYSIS  OF  SENSATIONS        305 

impulses  in  the  second  half.  An  effectual  summation  is 
therefore  excluded.  It  would  only  be  possible  if  the 
resonator  could  be  made  more  receptive  of  one  kind  of 
impulse  than  of  the  other,  and  more  receptive  in  the  first 
half  of  the  duration  of  its  vibration.  We  can  easily  see 
how  this  way  of  considering  the  matter  involves  the  re- 
jection of  Young's  explanation  of  combination  tones  by 
means  of  rapid  beats,  and  leads,  on  the  other  hand,  to 
Helmholtz's  theory  of  combination  tones,  while  preserving 
the  theory  of  resonance.  It  would  seem,  however,  that 
the  physical  relations  which  Helmholtz  had  to  assume  do 
not  exist  in  the  circumstances  under  which  combination 
tones  are  heard.  But  it  is  quite  conceivable  that  a  nervous 
organ  should  be  unequally  receptive  of  opposite  impulses, 
and  likewise  should  be  receptive  in  different  degrees  at 
different  stages  of  its  excitation.  For  an  organ  does  not 
simply  follow  the  forces  that  act  upon  it,  but  contains  a 
store  of  energy  upon  which  those  forces  only  act  by  liberat- 
ing the  energy.  In  this  way  Young's  mistake,  and  the 
presumably  unsuccessful  attempt  of  Helmholtz  to  improve 
on  Young's  theory,  will  have  led  to  an  important  new  point 
of  view. 

21. 

The  theory  of  Helmholtz  as  to  tone-sensations  seemed, 
when  it  was  first  promulgated,  to  be  an  admirably  complete 
and  classical  achievement.  Yet,  on  a  fundamental  exami- 
nation, it  has  not  been  able  to  stand  against  criticism. 
And  this  criticism  was  in  no  sense  captious,  as  is  suffi- 
ciently evident  from  the  fact  that  the  attacks  of  the  different 
critics,  in  spite  of  all  individual  peculiarities,  were  directed 


306        THE  ANALYSIS  OF  SENSATIONS 

against  the  same  points  and  took  the  same  direction.  The 
result  of  all  this  criticism  seems  to  be  that  the  main  problem 
has  been  put  back  almost  to  the  point  at  which  it  stood 
before  Helmholtz  wrote.  The  effect  of  this  might  be 
tragic,  if  it  were  ever  legitimate  to  look  at  the  matter  from 
the  point  of  view  of  a  single  person. 

But  the  achievement  of  Helmholtz,  open  to  attack 
though  it  may  be  on  certain  sides,  must  not  be  underrated. 
His  work,  apart  from  the  positive  increase  of  knowledge 
which  we  owe  to  it,  has  brought  life  and  movement  into 
the  whole  question ;  it  has  encouraged  inquirers  to  make 
new  experiments,  and  has  provided  the  stimulus  for  a  mass 
of  new  investigations ;  new  prospects  have  been  opened  up, 
and  possible  ways  of  going  wrong  have  been  definitely 
closed  for  ever.  New  experiments  and  criticisms  are 
made  all  the  easier  by  the  existence  of  some  positive  work 
from  which  to  take  their  start. 

In  thinking  that  a  task,  which  provides  ample  work  for 
psychologists  and  physiologists  as  well  as  for  physicists, 
could  be  mastered,  in  all  its  main  features,  from  physical 
points  of  view,  Helmholtz  was  doubtless  under  a  delusion. 
Even  those  friends  and  contemporaries  of  his  who,  about 
the  middle  of  the  last  century,  founded  the  physical  school 
of  physiology  in  co-operation  with  him,  have  had  to  recog- 
nize that  the  fragment  of  inorganic  physics  which  we  have 
conquered,  is  far  from  being  the  whole  world.  The 
"Doctrine  of  Tone-Sensations"  is  the  speculation  of  a 
genius,  the  expression  of  an  artistic  intuition,  which  points 
the  way — though  it  be  only  by  the  symbolism  of  a  physical 
analogy,  and  as  in  a  picture — along  which  further  research 
will  have  to  advance.  We  must  therefore  be  careful  not  to 


THE  ANALYSIS  OF  SENSATIONS        307 

throw  overboard  much  that  is  valuable  along  with  the 
deficiencies  that  have  to  be  set  aside.  For  what  reasons 
Helmholtz  himself  took  so  little  notice  of  criticism,  I  do 
not  know.  But  in  the  last  disposition  which  he  made, 
according  to  which  the  text  of  the  Tone- Sensations  was 
to  remain  unaltered  after  his  death,  I  think  that  he  acted 
rightly. 

22. 

To  a  person  accustomed  to  looking  at  things  from  the 
point  of  view  of  the  theory  of  evolution,  the  high  develop- 
ment of  modern  music  and  the  spontaneous  and  sudden 
appearance  of  great  musical  talent  seem,  at  first  glance,  a 
most  singular  and  mysterious  phenomenon.  What  can  this 
remarkable  development  of  the  power  of  hearing  have  to  do 
with  the  preservation  of  the  species?  Does  it  not  far 
exceed  the  measure  of  the  necessary  or  the  merely  useful  ? 
What  can  possibly  be  the  significance  of  a  fine  discrimina- 
tion of  pitch  ?  Of  what  use  to  us  is  the  sense  of  intervals, 
or  of  the  acoustic  colorings  of  orchestral  music  ? 

As  a  matter  of  fact,  the  same  question  may  be  proposed 
with  reference  to  every  art,  no  matter  from  what  province 
of  sense  its  material  is  derived.  The  question  is  pertinent, 
also,  with  regard  to  the  intelligence  of  a  Newton,  an  Euler, 
or  their  like,  which  apparently  far  transcends  the  necessary 
measure.  But  the  question  is  most  obvious  with  reference 
to  music,  which  satisfies  no  practical  need  and  for  the  most 
part  depicts  nothing.  Music,  however,  is  closely  allied  to 
the  decorative  arts.  In  order  to  be  able  to  see,  a  person 
must  have  the  power  of  distinguishing  the  directions  of  lines. 
If  he  has  a  fine  power  of  distinction,  such  a  person  may 


308        THE  ANALYSIS  OF  SENSATIONS 

acquire,  as  a  sort  of  collateral  product  of  his  education,  a 
feeling  for  agreeable  combinations  of  lines.  The  case  is  the 
same  with  the  sense  of  color-harmony  following  upon  the 
development  of  the  power  of  distinguishing  colors,  and  so, 
too,  it  undoubtedly  is  with  respect  to  music. 

We  must  bear  in  mind  that  what  we  call  talent  and 
genius,  however  gigantic  their  achievements  may  appear  to 
us,  constitute  but  a  slight  departure  from  normal  endow- 
ment. Talent  may  be  resolved  into  the  possession  of 
psychical  power  slightly  above  the  average  'in  a  certain 
province.  And  as  for  genius,  it  is  talent  supplemented  by 
a  capacity  of  adaptation  extending  beyond  the  youthful 
period,  and  by  the  retention  of  freedom  to  overstep  routine 
barriers.  The  naivety  of  the  child  delights  us,  and  produces 
almost  always  the  impression  of  genius.  But  this  impres- 
sion as  a  rule  quickly  disappears,  and  we  perceive  that  the 
very  same  utterances  which,  as  adults,  we  are  wont  to 
ascribe  to  freedom,  have  their  source,  in  the  child,  in  a 
lack  of  fixed  character. 

Talent  and  genius,  as  Weismann  has  aptly  shown,1  do 
not  make  their  appearance  slowly  and  by  degrees  in  the 
course  of  generations ;  nor  can  they  be  the  result  of  ac- 
cumulated effort  and  practice  on  the  part  of  ancestors ;  but 
they  manifest  themselves  spontaneously  and  suddenly. 
Taken  in  connexion  with  what  has  been  said  above,  this, 
too,  is  intelligible,  if  we  will  but  reflect  that  descendants  are 
not  exact  reproductions  of  their  immediate  ancestors,  but 
exhibit  the  qualities  both  of  their  immediate  and  of  their 
more  distant  ancestors  and  relatives  with  some  variations, 

1  Weismann,  Ueber  die  Vererbung.  Jena,  1883  (English  translation, 
Clarendon  Press,  Oxford,  1889),  p.  43. 


THE  ANALYSIS  OF  SENSATIONS        309 

now  slightly  diminished,  now  slightly  augmented  in  amount. 
The  comparison  of  several  children  of  the  same  two  parents 
is  very  instructive  on  this  point.  To  deny  the  influence  of 
pedigree  on  psychical  dispositions  would  be  as  unreasonable 
as  to  reduce  everything  to  it,  as  is  done,  whether  from 
narrow-mindedness  or  dishonesty,  by  modern  fanatics  on 
the  question  of  race.  Surely  everyone  knows  from  his  own 
experience  what  rich  psychical  acquisitions  he  owes  to  his 
cultural  environment,  to  the  influence  of  long  vanished 
generations,  and  to  his  contemporaries.  The  factors  of 
development  do  not  suddenly  become  inoperative  in  post- 
embryonic  life.1 

1  Cf.    the  sound  and  sober  view  of  R.   Wallaschek,  Anfdnge  der 
Tonkunst)  Leipzig,  1903,  pp.  291-298. 


XIV.  INFLUENCE  OF  THE  PRECED- 
ING INVESTIGATIONS  ON  OUR 
CONCEPTION  OF  PHYSICS.1 

i. 

WHAT  gain  does  physics  derive  from  the  preceding  in- 
vestigations ?  In  the  first  place,  a  very  widespread 
prejudice  is  removed,  and  with  it,  a  barrier.  There  is  no  rift 
between  the  psychical  and  the  physical,  no  inside  and  outside, 
no  "  sensation  "  to  which  an  external  "  thing,"  different  from 
sensation,  corresponds.  There  is  but  one  kind  of  elements, 
out  of  which  this  supposed  inside  and  outside  are  formed 
— elements  which  are  themselves  inside  or  outside,  according 
to  the  aspect  in  which,  for  the  time  being,  they  are  viewed. 
The  world  of  sense  belongs  both  to  the  physical  and  the 
psychical  domain  alike.  As,  in  studying  the  behaviour  of 
gases,  by  disregarding  variations  of  temperature  we  reach 
Mariotte's  law,  but  by  expressly  considering  them,  Gay 

1  I  have  partly  discussed  the  questions  considered  in  this  chapter, 
before  (see  my  History  and  Root  of  the  Principle  of  the  Conservation 
of  Energy \  translated  by  P.  E.  B.  Jourdain,  Chicago,  Open  Court 
Publishing  Co.,  1911,  and  also  the  essay  on  "The  Economical  Nature 
of  Physical  Inquiry,"  first  published  in  1882,  and  now  in  my  Popular 
Scientific  Lectures,  Chicago.  1894,  and  see  my  Mechanik  and 
Warmelehre).  With  regard  to  the  idea  of  concepts  as  labor-saving 
instruments,  the  late  Prof.  W.  James  directed  in  conversation  my 
attention  to  points  of  agreement  between  my  writings  and  his  essay 
on  "The  Sentiment  of  Rationality"  (Mind,  Vol.  IV.,  p.  317,  July 
1879).  This  essay,  written  with  refreshing  vigor  and  impartiality,  will 
be  perused  by  everyone  with  pleasure  and  profit. 

310 


THE  ANALYSIS  OF  SENSATIONS        311 

Lussac's,  while  throughout  our  object  of  investigation 
remains  the  same ;  so,  too,  we  are  studying  physics  in  its 
broadest  signification  when  in  searching  into  the  connexions 
of  the  world  of  sense  we  leave  our  own  body  entirely  out 
of  account;  whereas  we  are  studying  the  psychology  or 
physiology  of  the  senses  when  we  direct  our  main  attention 
to  the  body  and  above  all  to  our  nervous  system.  Our 
body,  like  every  other,  is  part  of  the  world  of  sense ;  the 
boundary-line  between  the  physical  and  the  psychical  is 
solely  practical  and  conventional.  If,  for  the  higher  pur- 
poses of  science,  we  erase  this  dividing-line,  and  consider  all 
connexions  as  equivalent,  new  paths  of  investigation  cannot 
fail  to  be  opened  up. 

We  must  regard  it  as  an  additional  gain  that  the  physicist 
is  now  no  longer  overawed  by  the  traditional  intellectual 
implements  of  physics.  If  ordinary  "matter"  must  be 
regarded  merely  as  a  highly  natural,  unconsciously  con- 
structed mental  symbol  for  a  relatively  stable  complex  of 
sensational  elements,  much  more  must  this  be  the  case 
with  the  artificial  hypothetical  atoms  and  molecules  of 
physics  and  chemistry.  The  value  of  these  implements  for 
their  special,  limited  purposes  is  not  one  whit  destroyed. 
As  before,  they  remain  economical  ways  of  symbolizing 
experience.  But  we  have  as  little  right  to  expect  from 
them,  as  from  the  symbols  of  algebra,  more  than  we  have 
put  into  them,  and  certainly  not  more  enlightenment  and 
revelation  than  from  experience  itself.  We  are  on  our 
guard  now,  even  in  the  province  of  physics,  against  over- 
estimating the  value  of  our  symbols.  Still  less,  therefore,  will 
the  monstrous  idea  of  employing  atoms  to  explain  psychical 
processes  ever  get  possession  of  us;  seeing  that  atoms 


312         THE  ANALYSIS  OF  SENSATIONS 

are  but  the  symbols  of  those  peculiar  complexes  of  sensa- 
tional elements  which  we  meet  with  in  the  narrow  domains 
of  physics  and  chemistry. 

2. 

The  fundamental  views  of  mankind  are  formed  by  a 
natural  process  of  adaptation  to  a  narrower  or  wider  sphere 
of  experience  and  thought.  It  may  be  that  the  physicist  is 
still  satisfied  with  the  notion  of  a  rigid  matter,  of  which  the 
only  changes  are  movements,  or  changes  of  place.  Of  such 
a  thing  as  this  the  physiologist  or  psychologist  can  make 
nothing  at  all.  But  any  one  who  has  in  mind  the  gather- 
ing up  of  the  sciences  into  a  single  whole,  has  to  look  for  a 
conception  to  which  he  can  hold  in  every  department  of 
science.  Now  if  we  resolve  the  whole  material  world  into 
elements  which  at  the  same  time  are  also  elements  of  the 
psychical  world  and,  as  such,  are  commonly  called  sensa- 
tions ;  if,  further,  we  regard  it  as  the  sole  task  of  science 
to  inquire  into  the  connexion  and  combination  of  these 
elements,  which  are  of  the  same  nature  in  all  departments, 
and  into  their  mutual  dependence  on  one  another ;  we  may 
then  reasonably  expect  to  build  a  unified  monistic  structure 
upon  this  conception,  and  thus  to  get  rid  of  the  distressing 
confusions  of  dualism.  Indeed,  it  is  by  regarding  matter  as 
something  absolutely  stable  and  immutable  that  we  actually 
destroy  the  connexion  between  physics  and  physiology. 

Epistemological  criticism  can  indeed  do  no  one  any 
harm,  but  the  specialist, — the  physicist,  for  instance, — has 
no  reason  to  allow  himself  to  be  troubled  overmuch  by 
such  speculations.  Acuteness  of  observation  and  a  felicitous 
instinct  are  very  safe  guides  fcr  him.  His  conceptions,  in 


THE  ANALYSIS  OF  SENSATIONS        313 

so  far  as  they  prove  to  be  inadequate,  will  be  best  and  most 
quickly  corrected  by  the  facts.  But  when  it  is  a  question 
of  bringing  into  connexion  two  adjacent  departments,  each 
of  which  has  been  developed  in  its  special  and  peculiar  way, 
the  connexion  cannot  be  effected  by  means  of  the  limited 
conceptions  of  a  narrow  special  department.  By  means  of 
more  general  considerations,  conceptions  have  to  be  created 
which  shall  be  adequate  for  the  wider  domain.  Every 
physicist  is  not  an  epistemologist,  nor  ought  every  physicist 
to  be  one,  even  if  it  were  possible.  Special  research 
demands  a  man's  full  energies ;  but  so  does  epistemology. 
Not  long  after  the  first  edition  of  this  book  was  published, 
I  was  lectured  by  a  physicist  on  the  misguided  way  in  which 
I  had  conceived  my  task.  In  his  opinion,  it  was  impossible 
to  analyse  the  sensations  as  long  as  the  paths  of  the  atoms 
in  the  brain  were  unknown;  and  when  they  were  known 
everything  else  would  follow  of  itself.  Of  course  I  had  not 
much  use  for  utterances  such  as  these,  which,  had  I  been  a 
young  man  of  the  period  of  Laplace,  might  have  fallen  upon 
fertile  ground  and  have  developed  into  a  psychological 
theory  based  on  "  concealed  movements."  The  effect 
which  they  had  was,  however,  to  make  me  offer  a  silent 
apology  to  Dubois-Reymond  with  his  Ignorabimus^ — a 
dictum  which  up  to  that  moment  I  had  regarded  as  the 
greatest  mistake.  After  all,  Dubois-Reymond's  recognition 
of  the  insolubility  of  his  problem  was  an  immense  step  in 
advance ;  this  recognition  removed  a  weight  from  many 
men's  minds,  as  is  shewn  by  the  success  of  his  work,  a 
success  which  is  otherwise  scarcely  intelligible.1  He  did 

1  Dubois-Reymond,   Ueber  die  Grenzen  des  Naturerkennens,   1872, 
4th.  ed. 


314        THE  ANALYSIS  OF  SENSATIONS 

not,  indeed,  take  the  further  important  step  of  seeing  that 
the  recognition  of  a  problem  as  insoluble  in  principle,  must 
depend  on  a  mistaken  way  of  stating  the  question.  For  he 
too,  like  countless  others,  took  the  instruments  of  a  special 
science  to  be  the  actual  world. 


The  sciences  may  be  distinguished  according  to  the 
matter  of  which  they  treat,  as  also  by  their  manner  of  treat- 
ing it.  But  all  science  has  for  its  aim  the  representation  of 
facts  in  thought,  either  for  practical  ends,  or  for  removing 
intellectual  discomfort.  Resuming  the  terminology  of 
the  "Introductory  Remarks,"  science,  we  may  say,  arises 
when  the  combination  of  the  other  elements  is  imitated  by 
the  elements  a  (3  7.  .  .  .  For  example,  physics  (in  its 
broadest  signification)  arises  by  the  representative  repro- 
duction of  the  elements  A  B  C  in  their  relations  to  one 
another;  the  physiology  or  psychology  of  the  senses,  through 
reproducing  in  like  manner  the  relations  of  A  B  C  .  .  .  to 
K L  M  .  .  . ;  physiology,  through  reproducing  the  relations 
of  K  L  M  ...  to  one  another  and  to  A  B  C  .  .  . ;  while 
the  reproducing  of  the  a  /5  7  ...  themselves  by  other 
a  /3  7  .  .  .  leads  to  the  psychological  sciences  proper. 

Now  one  might  be  of  the  opinion,  say,  with  respect  to 
physics,  that  the  portrayal  of  the  sense-given  facts  is  of  less 
importance  than  the  atoms,  forces,  and  laws  which  form,  so 
to  speak,  the  nucleus  of  the  sense-given  facts.  But  un- 
biassed reflexion  discloses  that  every  practical  and  intel- 
lectual need  is  satisfied  the  moment  our  thoughts  have 
acquired  the  power  to  represent  the  facts  of  the  senses 


THE  ANALYSIS  OF  SENSATIONS        315 

completely.  Such  representation,  consequently,  is  the  end 
and  aim  of  physics ;  while  atoms,  forces,  and  laws  are 
merely  means  facilitating  the  representation.  Their  value 
extends  as  far,  and  as  far  only,  as  the  help  they  afford. 


Our  knowledge  of  a  natural  phenomenon,  say  of  -an 
earthquake,  is  as  complete  as  possible  when  our  thoughts 
so  marshal  before  the  eye  of  the  mind  all  the  relevant  sense- 
given  facts  of  the  case  that  they  may  be  regarded  almost  as 
a  substitute  for  the  phenomenon  itself,  and  the  facts  appear 
to  us  as  old  familiar  figures,  having  no  power  to  occasion 
surprise.  When,  in  imagination,  we  hear  the  subterranean 
thunders,  feel  the  oscillation  of  the  earth,  figure  to  ourselves 
the  sensation  produced  by  the  rising  and  sinking  of  the 
ground,  the  cracking  of  the  walls,  the  falling  of  the  plaster, 
the  movement  of  the  furniture  and  the  pictures,  the  stopping 
of  the  clocks,  the  rattling  and  smashing  of  windows,  the 
wrenching  of  the  door-posts,  the  jamming  of  the  doors; 
when  we  see  in  mind  the  oncoming  undulation  passing  over 
a  forest  as  lightly  as  a  gust  of  wind  over  a  field  of  grain, 
breaking  the  branches  of  the  trees ;  when  we  see  the  town 
enveloped  in  a  cloud  of  dust,  hear  the  bells  begin  to  ring 
in  the  towers ;  further,  when  the  subterranean  processes, 
which  are  at  present  unknown  to  us,  shall  stand  out  in  full 
sensational  reality  before  our  eyes,  so  that  we  shall  see  the 
earthquake  advancing  as  we  see  a  waggon  approaching  in 
the  distance  till  finally  we  hear  the  earth  shaking  beneath 
our  feet, — then  more  insight  than  this  we  cannot  have,  and 
more  we  do  not  require.  If  we  cannot  combine  the  partial 


316        THE  ANALYSIS  OF  SENSATIONS 

facts  in  their  right  proportions  without  the  aid  of  certain 
auxiliary  mathematical  conceptions  or  geometrical  construc- 
tions, it  yet  remains  true  that  these  constructions  merely 
enable  our  thoughts  to  grasp  gradually  and  piecemeal  what 
they  are  unable  to  grasp  all  at  once.  But  these  auxiliary 
conceptions  would  be  devoid  of  value,  could  we  not  reach, 
by  their  help,  the  graphic  representation  of  the  sense-given 
facts. 

When  I  see  in  thought  a  white  beam  of  light  which  falls 
upon  a  prism  issue  forth  in  a  fan-shaped  band  of  colors 
having  certain  angles  which  I  can  specify  beforehand  ;  when 
1  see  the  real  spectrum-image,  obtained  upon  a  screen  by 
interposing  a  lens,  with  Fraunhofer's  lines  occurring  in  it  at 
points  determinable  in  advance ;  when  I  see,  in  my  mind, 
how  these  lines  alter  their  position  on  the  prism  being 
turned,  on  its  substance  being  changed,  or  on  the  ther- 
mometer in  contact  with  it  altering  its  register,  then  I  know 
all  that  I  can  require.  All  auxiliary  conceptions,  laws,  and 
formulae,  are  but  quantitative  norms,  regulating  my  sensory 
representation  of  the  facts.  The  latter  is  the  end,  the 
former  are  the  means. 


The  adaptation  of  thoughts  to  facts,  accordingly,  is  the 
aim  of  all  scientific  research.  In  this,  science  only  deliber- 
ately and  consciously  pursues  what  in  daily  life  goes  on 
unnoticed  and  of  its  own  accord.  As  soon  as  we  become 
capable  of  self-observation,  we  find  our  thoughts,  in  large 
measure,  already  adjusted  to  the  facts.  Our  thoughts 
marshal  the  elements  before  us  in  groups  copying  the  order 
of  the  sense-given  facts.  But  the  limited  supply  of  thoughts 


THE  ANALYSIS  OF  SENSATIONS        317 

cannot  keep  pace  with  the  constantly  augmenting  sweep  of 
experience.  Almost  every  new  fact  necessitates  a  new 
adaptation,  which  finds  its  expression  in  the  operation  of 
judgment. 

This  process  is  easily  followed  in  children.  A  child,  on 
its  first  visit  from  the  town  to  the  country,  strays,  for 
instance,  into  a  large  meadow,  looks  about,  and  says 
wonderingly :  "We  are  in  a  ball.  The  world  is  a  blue 
ball."  l  Here  we  have  two  judgments.  What  is  the  process 
accompanying  their  formation?  In  the  first  instance,  the 
already  existing  sensational  representation  "we"  (himself 
and  his  companions)  is  filled  out  into  a  single  image  by 
means  of  the  representation  of  a  ball,  which  also  already 
existed.  Similarly,  in  the  second  judgment,  the  image  of 
the  "  world "  (/.*.,  all  the  objects  of  the  environment)  is 
supplemented  by  combination  with  the  image  of  an  envelop 
ing  blue  ball  (the  representation  of  which  must  also  have 
been  present,  since  otherwise  the  name  for  it  would  have 
been  wanting).  A  judgment  is  thus  always  a  supplement- 
ing of  a  sensational  presentation  in  order  to  represent  more 
completely  a  sensational  fact.  If  the  judgment  can  be 
expressed  in  words,  then  the  new  presentation  is  never 
more  than  a  combination  of  formerly  established  memory- 
images,  which  can  also  be  elicited  in  a  person  addressed 
by  words. 

The  process  of  judgment,  therefore,  in  the  present  case, 
consists  in  the  enrichment,  extension,  and  supplementation 

1  This  example  is  not  fictitious,  but  was  observed  in  the  case  of  my 
three-year-old  child.  In  this  case  what  is  actually  attested  is  a  physio- 
logical fact,  but  this  has  only  been  recognized  at  a  late  stage.  Scientific 
astronomy  begins  in  antiquity  with  similar  naif  assertions,  which  it 
thinks  are  physical. 


3i8        THE  ANALYSIS  OF  SENSATIONS 

of  sensational  presentations  by  other  sensational  presenta- 
tions under  the  guidance  of  sense-given  facts.  If  the  pro- 
cess is  over,  and  the  image  has  assumed  a  familiar  shape, 
making  its  appearance  in  consciousness  as  a  completed 
presentation,  then  we  have  no  longer  to  do  with  a  judgment 
but  merely  with  a  simple  memory.1  It  is  to  the  formation 
of  such  intuitive  knowledge,  as  Locke  calls  it,  that  natural 
science  and  mathematics  mainly  owe  their  growth.  Con- 
sider, for  example,  the  following  statements  :  (i)  the  tree 
has  a  root ;  (2)  the  frog  has  no  claws  ;  (3)  the  caterpillar  is 
transformed  into  a  butterfly ;  (4)  weak  sulphuric  acid  dis- 
solves zinc ;  (5)  friction  electrifies  glass ;  (6)  an  electric 
current  deflects  a  magnetic  needle ;  (?)  a  cube  has  six 
surfaces,  eight  corners,  twelve  edges.  The  first  statement 
contains  a  spatial  extension  of  the  presentation  "  tree " ; 
the  second  a  correction  of  a  presentation  too  hastily 
generalized  from  habit ;  the  third,  fourth,  fifth,  and  sixth 
contain  temporal  extensions  of  their  respective  presentations. 


1  I  cannot  here  enter  upon  an  examination  of  the  process  of  judgment 
as  such.  But  among  recent  works  on  the  subject  I  should  like  to  draw 
special  attention  to  W.  Jerusalem's  Die  Urteilsfiinktion  (Vienna,  1895). 
Though  my  own  position  is  not  that  of  the  author's,  I  nevertheless  have 
been  greatly  stimulated  and  instructed  by  many  of  the  investigations  of 
special  points  contained  in  his  book.  The  physiological  aspects,  and 
in  particular  the  biological  function  of  judgment,  are  set  forth  in  a  very 
lively  way.  His  conception  of  the  subject  in  judgment  as  a  centre  of 
force  can  scarcely  be  called  felicitous.  On  the  other  hand,  it  will 
certainly  be  readily  admitted  that  in  the  early  stages  of  culture  and  of 
the  formation  of  language  anthropomorphic  conceptions  exerted  much 
influence.  Other  questions  of  a  different  kind  are  discussed  by  A. 
Stohrin  7heorieder  Namen  (1889),  Die  Vieldeutigkeit des  (7rtet/s(i&9$), 
and  Algebra  der  Grammatik  (1898).  Of  these  works,  those  concerned 
with  the  relation  between  logic  and  grammar  seem  to  me  the  most 
interesting. 


THE  ANALYSIS  OF  SENSATIONS        319 

The   seventh    proposition   is   an   example   of  geometrical 
intuitive  knowledge. 

6. 

Intuitive  knowledge  of  the  sort  just  described  impresses 
itself  upon  the  memory,  and  makes  its  appearance  in  the 
form  of  recollections  which  spontaneously  supplement  every 
fact  presented  by  the  senses.  The  various  facts  are  not 
exactly  alike.  But  the  component  parts  of  the  sensational 
presentation  which  are  common  to  different  cases  are 
emphasized,  and  so  we  reach  a  principle  which  holds  a 
paramount  place  in  memory — the  principle  of  broadest 
possible  generalization  or  continuity.  On  the  other  hand,  if 
memory  is  to  do  justice  to  the  complexity  of  facts,  and  be 
of  real  practical  use,  it  must  conform  to  the  principle  of 
sufficient  differentiation.  Even  the  animal  is  reminded,  by 
soft,  bright  red  and  yellow  fruits  (seen  without  exertion  on 
the  tree),  of  their  sweet  taste,  and  by  green  hard  fruits 
(which  are  seen  with  difficulty),  of  their  sour  taste.  The 
insect-hunting  monkey  snatches  at  everything  that  buzzes 
and  flies,  but  avoids  the  yellow  and  black  fly,  the  wasp. 
Here  we  have  expressed,  distinctly  enough,  the  combined 
effort  for  the  greatest  possible  generalization  and  continuity 
and  lot  practically  sufficient  differentiation  of  memory.  And 
both  ends  are  attained  by  the  same  means,  the  selection  and 
emphasis  of  those  particular  elements  of  the  sensational  pre- 
sentations which  are  determinative  of  the  direction  which 
the  thought  must  pursue  to  suit  the  experience.  The 
physicist  proceeds  in  quite  an  analogous  manner,  when  he 
says  (generalizing)  :  All  transparent  solids  refract  incident 
light  towards  the  perpendicular,  and  when  he  adds  (differ- 


320        THE  ANALYSIS  OF  SENSATIONS 

entiating) :  amorphous  bodies  and  isomeric  crystals  simply, 
the  rest  doubly. 


A  great  part  of  our  mental  adaptation  takes  place  un- 
consciously and  involuntarily,  under  the  guidance  of  the 
facts  presented  to  the  senses.  If  this  adaptation  has 
become  sufficiently  comprehensive  to  embrace  the  vast 
majority  of  the  occurring  facts,  and  subsequently  we  come 
upon  a  fact  which  runs  violently  counter  to  the  customary 
course  of  our  thought  without  our  being  able  to  discover  at 
once  the  determinative  factor  likely  to  lead  to  a  new  differ- 
entiation, then  a  problem  arises.  The  new,  unusual,  and 
marvellous  acts  as  a  stimulus,  which  irresistibly  attracts  the 
attention.  Practical  considerations,  or  even  bare  intellectual 
discomfort,  may  engender  the  will  to  remove  the  contradic- 
tion or  to  adapt  our  thoughts  to  the  new  fact.  Thus  arises 
purposive  thought-adaptation,  or  investigation. 

For  example,  we  have  all,  at  some  time  or  another,  quite 
contrary  to  the  common  run  of  our  experience,  observed  a 
lever  or  pulley  lifting  a  large  weight  by  means  of  a  small 
one.  We  seek  the  differentiating  factor,  which  cannot  be 
immediately  disclosed  to  us  by  the  fact  itself  as  given  to 
the  senses.  It  is  only  when,  comparing  various  similar 
facts,  we  have  noted  the  influence  of  the  weights,  and  of 
the  arms  of  the  lever,  and  by  our  own  exertions  have  reached 
the  abstract  concepts  of  "moment"  or  "work,"  that  the 
problem  is  solved.  "  Moment  "  or  "  work  "  is  the  differen- 
tiating element.  When  it  has  become  a  habit  of  thought  to 
pay  attention  to  "moment"  or  "work,"  the  problem  no 
longer  exists. 


THE  ANALYSIS  OF  SENSATIONS        321 


8. 

What  do  we  do  when  we  abstract  ?  What  is  an  abstrac- 
tion ?  What  is  a  concept  ?  Is  there  a  sensational  presentation- 
image  corresponding  to  the  concept  ?  I  cannot  represent 
to  myself  a  man  in  general.  I  can  at  most  represent  to 
myself  a  particular  man,  or  perhaps  one  combining  such 
accidental  peculiarities  of  different  men  as  are  not  exclusive 
of  each  other.  A  universal  triangle,  which  is  at  once  right- 
angled  and  equilateral,  cannot  be  imagined.  Further,  the 
image  thus  rising  into  consciousness  at  the  name  of  the  con- 
cept, and  accompanying  the  conceptual  process,  is  not  the 
concept.  In  fact,  generally,  words,  being  designations  which 
from  necessity  must  be  used  to  describe  many  particular 
presentations,  are  far  from  corresponding  completely  to  any 
concept.  A  child  who  has  seen  for  the  first  time  a  black 
dog  and  heard  it  named,  soon  afterward  calls  a  large  and 
swiftly-running  black  beetle,  "dog";  or  a  pig  or  a  sheep, 
"dog."1  Any  similarity  whatever  reminding  him  of  the 
presentation  to  which  the  name  was  first  given  naturally 
leads  to  the  use  of  the  same  name.  The  point  of  similarity 
need  not  be  at  all  the  same  in  the  successive  cases.  It  may 
reside,  for  instance,  at  one  time,  in  the  color,  at  another 
in  the  motion,  at  another  in  the  form,  at  another  in  the 
external  covering ;  and  so  on.  Thus  there  is  no  question 
of  a  concept.  Thus  a  child  calls  the  feathers  of  a  bird 
"hairs";  the  horns  of  a  cow  " feelers ;; ;  a  shaving-brush, 

1  Thus  the  Marcomanni  called  the  lions  sent  across  the  Danube  by 
the  Romans  "dogs,"  and  the  lonians  called  the  xd-pfa1  °f  tne  Nile 
"crocodiles  "  from  their  likeness  to  the  lizards  (KpoK65ei\oi)  which,  in 
Ionia,  live  in  the  walls.     (Herodotos,  II.,  69.) 
X 


322        THE  ANALYSIS  OF  SENSATIONS 

its  father's  beard,  and  the  down  of  a  dandelion,  without  dis- 
tinction, "shaving-brush";  and  so  on.1  Most  adults  treat 
words  in  the  same  manner,  only  less  noticeably  so,  because 
they  have  a  larger  vocabulary  at  their  disposal.  The  illiterate 
man  calls  a  rectangle  a  "  square  " ;  occasionally  he  also  calls 
a  cube  a  "  square,"  because  of  its  rectangular  boundaries. 
The  science  of  language,  and  a  number  of  authenticated 
historical  examples,  shew  that  even  nations  do  not  act 
differently.2 

A  concept  is  never  simply  a  completed  presentation. 
In  using  a  word  denoting  a  concept,  there  is  nothing  in- 
volved in  the  word  but  a  simple  impulse  to  perform  some 
familiar  sensory  operation,  as  the  result  of  which  a  definite 
sensational  element  (the  mark  of  the  concept)  is  obtained. 
For  example,  when  I  think  of  the  concept  "heptagon,"  I 
enumerate  the  angles  of  a  figure  visibly  before  me  or  of 
its  image  in  my  consciousness;  and  when  in  so  doing  I 
reach  seven,  in  which  case  the  sound,  the  numeral,  or  my 
finger  may  announce  the  sensational  mark  of  the  number, 
then  by  this  very  act  the  given  presentation  falls  under 
the  given  concept.  In  speaking  of  a  "square  number," 
I  seek  to  resolve  the  number  given  into  components 
typified  by  the  operation  5x5,  6x6,  etc.,  the  sensational 
characteristic  of  which,  namely,  the  equality  of  the  two 
factors  multiplied,  is  patent.  The  same  holds  good  of 
every  concept.  The  activity  excited  by  the  word  may  be 
made  up  of  a  number  of  operations,  one  of  which  may 
contain  the  other.  But  the  result  is  always  a  sensational 
element  which  was  not  present  before. 

1  All  these  examples  are  taken  from  actual  experience. 

2  See  W.  D.  Whitney,  Life  and  Growth  of  Language,  1875. 


THE  ANALYSIS  OF  SENSATIONS        323 

In  looking  at  or  in  imagining  a  heptagon,  the  fact  of 
its  having  seven  angles  need  not  be  present  to  my  mind. 
This  fact  is  distinctly  cognized  only  on  counting.  Fre- 
quently, the  new  sensational  element  may  be  so  obvious 
(as  it  is,  for  instance,  in  the  case  of  the  triangle)  that  the 
operation  of  counting  seems  unnecessary.  Such  cases, 
however,  are  exceptional,  and  constitute  the  main  source 
of  misunderstandings  concerning  the  nature  of  concepts. 
In  the  case  of  conic  sections  (the  ellipse,  parabola, 
hyperbola)  I  do  not  directly  see  that  these  curves  all 
fall  under  the  same  concept ;  but  I  can  discover  the  fact 
by  cutting  a  cone,  and  by  constructing  the  equation  for 
conies. 

When,  therefore,  we  apply  abstract  concepts  to  a  fact, 
the  fact  merely  acts  upon  us  as  an  impulse  to  a  sensa- 
tional activity,  which  introduces  new  sensational  elements, 
which  in  their  turn  may  determine  the  subsequent  course 
of  our  thought  in  harmony  with  the  fact.  By  this 
activity  we  enrich  and  extend  the  fact,  which  before 
was  too  meagre  for  us.  We  do  what  the  chemist  does 
with  his  colorless  solution  of  salts,  when  by  a  definite 
operation  he  elicits  from  it  a  yellow  or  brown  precipi- 
tate, which  has  the  power  to  differentiate  the  course  of 
his  thought.  The  concept  of  the  physicist  is  a  definite 
reaction-activity,  which  enriches  a  fact  with  new^sensational 
elements. 

A  small  measure  of  sensational  endowment  and  a  very 
low  degree  of  mobility  are  sufficient  for  the  formation  of 
concepts,  as  is  shewn  by  the  history  of  the  mental  develop- 
ment of  the  blind,  deaf  and  dumb  Laura  Bridgman,  which 
has  been  made  generally  accessible  by  Jerusalem's  interest- 


324        THE  ANALYSIS  OF  SENSATIONS 

ing  little  book.1  In  Laura  Bridgman  the  sense  of  smell 
wa*s  almost  entirely  lacking ;  her  only  channel  for  the  per- 
ception of  disturbances  and  sound-vibrations  was  the  soles 
of  her  feet  and  her  finger-tips — her  skin,  in  short;  yet 
she  succeeded  in  forming  simple  concepts.  By  walking 
about  and  by  moving  her  hands  she  discovers  the  tactual 
signs  (the  class-characteristics)  of  a  door,  a  chair,  a  knife, 
and  so  forth.  The  power  of  abstraction  does  not,  indeed, 
go  very  far.  The  most  abstract  concepts  to  which  she 
was  able  to  attain  seem  to  have  been  the  numbers.  On 
the  whole  her  mental  processes  remained,  naturally  enough, 
attached  to  specific  presentations.  Evidence  of  this  is 
afforded  by  her  taking  the  sums  in  a  school-book  to  be 
specially  intended  for  her  (op.  tit.,  p.  25),  and  her  idea 
that  heaven,  or  the  world  beyond,  was  a  school  (op.  tit., 
P-  3°)- 


To  revert  to  an  earlier  example,  when  we  see  a  lever, 
we  are  impelled  to  measure  the  length  of  its  arms,  to  weigh 
its  weights,  and  to  multiply  the  numbers  representing  the 
lengths  of  its  arms  by  the  numbers  representing  the  values 
of  its  weights.  If  the  same  sensational  numerical  symbol 
corresponds  to  both  products,  we  expect  equilibrium.  We 
have  thus  gained  a  new  sensational  element  which  was 
not  antecedently  given  in  the  bare  fact  itself,  but  which 
now  differentiates  the  course  of  our  thought.  If  we  will 
keep  well  in  mind  the  fact  that  conceptual  thought  is  a  re- 

1  W.  Jerusalem,  Laura  Bridgman,  Vienna,  Pichler,  1891.  Cp. 
also  L.  W.  Stern,  Helen  Keller,  Berlin,  1905;  Jerusalem,  "Marie 
Heurtin,"  Oesterreichische  ftundsckau,  Vol.  III.,  pp.  292,  426  (1905). 


THE  ANALYSIS  OF  SENSATIONS        325 

action-activity  which  must  be  thoroughly  practised,  we  shall 
understand  the  well-known  fact  that  no  one  can  familiarize 
himself  with  mathematics  or  physics  or  with  any  natural 
science  by  mere  reading  without  practical  exercise.  Under- 
standing here  depends  entirely  on  action.  In  fact,  it  is 
impossible  in  any  province  to  grasp  the  higher  abstractions 
without  a  practical  working  knowledge  of  its  details. 

Facts,  then,  are  extended  and  enriched,  and  ultimately 
again  simplified,  by  conceptual  handling.  For  when  the 
new  determinative  sensational  element  is  found  (say,  the 
number  representing  the  virtual  moments  of  the  lever), 
then  the  attention  is  directed  to  this  alone,  and  the  most 
diverse  groups  of  facts  are  found  to  resemble  and  not  to 
resemble  each  other  solely  in  virtue  of  this  element.  Thus 
here  also,  as  in  the  case  of  intuitive  knowledge,  everything 
is  reducible  to  the  discovery,  selection,  and  emphasis  of 
the  determinative  sensational  elements.  Investigation  here 
only  reaches  by  a  roundabout  way  what  is  immediately 
presented  to  intuitive  cognition. 

The  chemist  with  his  re-agents,  the  physicist  with  his  mea- 
suring-rod, scales,  and  galvanometer,  and  the  mathematician 
all  treat  facts  in  precisely  the  same  way  \  the  only  difference 
being  that  the  latter  needs  to  go  least  outside  the  elements 
a  j8  7  .  .  .  KL  M  in  his  extension  of  facts.  The  aids  of 
the  mathematician  are  always  conveniently  at  hand.  The 
investigator  and  all  his  thought  are  a  fragment  only  of 
nature,  like  everything  else.  There  is  no  real  chasm  between 
him  and*he  t/other  fragments.  All  elements  are  equivalent. 

On  the  preceding  theory,  the  essence  of  abstraction  is 
not  exhausted  by  terming  it  (with  Kant)  negative  attention. 
It  is  true  that,  in  abstracting,  the  attention  is  turned  away 


326        THE  ANALYSIS  OF  SENSATIONS 

from  many  sensational  elements,  but  on  the  other  hand,  it 
is  turned  towards  other  new  sensational  elements ;  and 
precisely  this  latter  fact  is  the  essential  feature.  Every 
abstraction  is  founded  on  the  prominence  given  to  certain 
sensational  elements. 

10. 

In  the  foregoing  exposition  of  my  views  I  have  left  what 
I  wrote  in  1886  unaltered;  but  at  the  same  time  I  should 
like  to  refer  the  reader  to  the  further  explanations  contained 
in  a  later  work  of  mine.1  In  the  second  edition  of  the 
Prinzipien  der  Wdrmekhre  (1900),  I  have  also  mentioned 
the  works  of  H.  Gomperz  and  Ribot,  which  have  appeared 
since  1897  ;  these  works  contain  investigations  which  in 
many  respects  have  a  certain  affinity  to  my  own.  Both 
Gomperz  and  Ribot  exclude  scientific  concepts  from  the 
scope  of  their  inquiry,  and  treat  only  of  such  vulgar  con- 
cepts as  have  been  fixed  in  the  words  of  the  common 
speech  of  everyday  intercourse.  I,  on  the  contrary,  am  of 
the  opinion  that  the  nature  of  concepts  is  necessarily  much 
more  clearly  displayed  in  scientific  concepts,  which  have 
been  consciously  formed  and  applied,  than  in  vulgar 
concepts.  The  latter  are  so  vague  that  they  can  scarcely 
be  reckoned  as  proper  concepts  at  all.  The  words  of 
ordinary  speech  are  simply  familiar  signs  which  occasion 
equally  familiar  habits  of  thought.  The  conceptual  content 
of  such  words,  in  so  far  as  it  has  any  definite  form  at  all, 
is  scarcely  present  to  consciousness,  as  Ribot  also  found 
by  his  statistical  experiments.  I  have  no  doubt  that,  if 

1  Prinzipien  der  WtLrmekhre>  1896  ;   2nd  ed.,  1900,  pp.  415,  422. 


THE  ANALYSIS  OF  SENSATIONS        327 

Ribot  and  Gomperz  had  framed  their  inquiry  so  as  to 
include  scientific  concepts  also,  my  agreement  with  them 
would  be  even  more  far-reaching  than  it  actually  is. 

We  have  chosen  statical  moment  as  a  simple  example  of 
a  concept.  Complicated  concepts  will  require  a  complicated 
system  of  reactions,  drawing  upon  more  or  less  large  parts 
of  the  central  nervous  system,  and  helping  to  create  a 
correspondingly  complicated  system  of  sensational  elements 
characterizing  the  concept.  Probably  the  difficulties  pointed 
out  by  J.  von  Kries  are  not  insuperable  on  this  theory.1 

(Cf.  pp.  69,  70  above.) 

• 

ii. 

The  facts  given  by  the  senses,  therefore,  are  alike  the 
starting-point  and  the  goal  of  all  the  mental  adaptations  of 
the  physicist.  The  thoughts  which  follow  the  sense-given 
fact  immediately  are  the  most  familiar,  the  strongest,  and 
the  most  intuitive.  Where  we  cannot  at  once  follow  a  new 
fact,  the  strongest  and  most  familiar  thoughts  press  forward 
to  mould  it  into  a  richer  and  more  definite  shape.  This 
process  is  the  source  of  all  the  hypotheses  and  speculations 
of  science,  which  all  find  their  justification  in  the  mental 
adaptation  that  develops  them  and  ultimately  gives  them 
birth.  Thus  we  think  of  the  planets  as  projectiles,  we  figure 
to  ourselves  an  electric  body  as  covered  with  a  fluid  that 
acts  at  a  distance,  we  think  of  heat  as  a  substance  that  passes 
from  one  body  to  another,  until  finally  the  new  facts  become 
as  familiar  and  as  intuitive  as  the  older  ones,  which  we  have 
used  as  mental  helps.  Even  where  immediate  intuition  is 

*J.  von  Kries,  Die  materiellen  Gmndlagen  der  Bewusstseinser- 
scheinungeti)  Freiburg  im  Breisgau,  1898. 


328        THE  ANALYSIS  OF  SENSATIONS 

out  of  the  question,  the  thoughts  of  the  physicist,  by  care- 
fully observing  the  principle  of  continuity  and  of  sufficient 
differentiation,  become  ordered  in  an  economically  assorted 
system  of  conceptual  reactions,  which  lead,  at  least  by  the 
shortest  path,  to  intuitive  knowledge.  All  calculations, 
constructions,  etc.,  are  merely  intermediate  means,  pro- 
ceeding step  by  step,  and  always  using  sense-perception  as 
a  support,  to  the  attainment  of  this  kind  of  intuition  in 
cases  where  it  cannot  be  attained  immediately. 

12. 

• 
Let  us  now  consider  the  results  of  mental  adaptation. 

Thoughts  can  adapt  themselves  only  to  what  is  constant 
in  the  facts  ;  it  is  only  the  mental  reconstruction  of  constant 
elements  that  can  yield  advantage  in  point  of  economy. 
Herein  is  contained  the  ultimate  ground  of  our  effort  for 
continuity  in  thought,  that  is,  for  the  preservation  of  the 
greatest  possible  constancy,  and  in  this  way,  too,  the  results 
of  the  adaptation  are  rendered  intelligible.1  Continuity, 
economy,  and  constancy  mutually  condition  one  another  • 
they  are  really  only  different  aspects  of  one  and  the  same 
property  of  all  sound  thinking. 


The  unconditionally  constant  we  term  substance.  I  see 
a  body  upon  turning  my  eyes  in  its  direction.  I  can  see 
it  without  touching  it,  I  can  touch  it  without  seeing  it. 
Although  the  actual  appearance  of  the  component  elements 

1  Cp.  my  The  Science  of  Mechanics,  translated  by  T.  J.  M'Cormack, 
Chicago,  Open  Court  Publishing  Co.,  1893,  P-  5O4- 


THE  ANALYSIS  OF  SENSATIONS        329 

of  the  complex  is  determined  in  this  way  by  certain  conditions, 
I  yet  have  these  conditions  too  absolutely  in  my  power  to 
appreciate  or  notice  them  markedly.  I  regard  the  body,  or 
the  complex  of  elements,  or  the  nucleus  of  this  complex, 
as  always  present,  whether,  for  the  moment,  it  is  the  object 
of  my  senses  or  not.  Having  always  ready  the  thought  of 
this  complex,  or,  symbolically,  the  thought  of  its  nucleus, 
I  gain  the  advantage  of  being  able  to  predict,  and  avoid 
the  disadvantage  of  being  surprised.  My  behaviour  is  the 
same  with  regard  to  the  chemical  elements,  which  also 
appear  to  me  unconditionally  constant.  Although  here  my 
mere  willing  it  is  not  sufficient  to  make  of  the  complexes  in 
question  sensational  facts,  and  although  in  the  present  case 
external  aids  (for  instance,  bodies  exterior  to  my  own  body) 
also  are  necessary,  I  yet  leave  these  aids  out  of  account 
as  soon  as  they  have  become  familiar  to  me,  and  look  upon 
the  chemical  elements  as  simply  constant.  The  man  who 
believes  in  atoms  treats  them  in  an  analogous  way. 

In  the  same  manner  as  with  the  complex  of  elements 
corresponding  to  a  body,  we  may  also  proceed,  on  a  higher 
plane  of  thought-adaptation,  with  entire  provinces  of  facts. 
In  speaking  of  electricity,  magnetism,  light,  and  heat,  even 
when  not  associating  special  substances  with  these  names, 
we  yet  ascribe  constancy  to  these  provinces  of  facts,  leaving 
entirely  out  of  account  the  familiar  conditions  under  which 
they  appear ;  and  we  hold  the  ideas  which  reproduce  them 
always  in  readiness,  thereby  gaining  an  advantage  similar 
to  that  explained  above.  When  I  say  a  body  is  "electric," 
far  more  memories  arise  in  my  mind,  and  my  expectations 
are  associated  with  far  more  definite  groups  of  facts,  than 
if  I  had  emphasized,  for  instance,  the  attractions  displayed 


330        THE  ANALYSIS  OF  SENSATIONS 

in  the  single  cases.  Yet  this  hypostasizing  may  have  its 
disadvantages,  also.  In  the  first  place,  in  proceeding  thus, 
we  always  follow  the  same  historical  paths.  It  may  be 
important,  however,  to  recognize  that  there  is  no  such 
thing  as  a  specific  electrical  fact,  that  every  such  fact  can 
just  as  well  be  regarded,  for  example,  as  a  chemical  one,  or 
as  a  thermal  one,  or  rather  that  all  physical  facts  are  made 
up,  ultimately,  of  the  same  sensational  elements  (colors, 
pressures,  spaces,  times),  and  that  we  are  merely  reminded 
by  the  term  "  electric  "  of  that  particular  form  in  which  we 
first  became  acquainted  with  the  fact. 

If  we  have  once  accustomed  ourselves  to  regard  the  body, 
to  and  from  which  we  can,  at  pleasure,  turn  our  glance  or 
our  hand,  as  constant,  then  it  is  easy  for  us  to  do  the  same 
in  cases  in  which  the  conditions  of  sensational  manifesta- 
tion lie  entirely  beyond  our  power — for  example,  in  the 
case  of  the  sun  and  moon,  which  we  cannot  touch,  or  of 
parts  of  the  world  which  we  have  seen  but  once  and  shall 
perhaps  never  see  again,  or  that  we  know  only  by  descrip- 
tion. Such  a  method  of  procedure  may  have  high  import- 
ance for  an  undisturbed  and  economical  conception  of  the 
world,  but  it  is  certainly  not  the  only  legitimate  method. 
It  would  be  merely  a  consistent  additional  step,  if  we  were 
to  regard  the  whole  past,  which  is,  indeed,  still  present  in 
its  vestiges  (since,  for  instance,  we  see  the  stars  where  they 
were  thousands  of  years  ago),  and  the  whole  future,  which 
is  present  in  germ  (since,  for  example,  our  solar  system  will 
be  seen  where  it  now  is,  thousands  of  years  hence),  as  con 
stant.  The  entire  passage  of  time,  in  fact,  is  dependent 
solely  on  conditions  of  our  sensibility.  Were  a  special 
purpose  given,  even  this  step  might  be  hazarded 


THE  ANALYSIS  OF  SENSATIONS        331 


14. 

Really  unconditioned  constancy  does  not  exist,  as  will 
be  evident  from  the  preceding  considerations.  We  attain 
to  the  idea  of  absolute  constancy  only  as  we  overlook  or 
underrate  conditions,  or  as  we  regard  them  as  always  given, 
or  as  we  deliberately  disregard  them.  There  is  only  one 
sort  of  constancy,  which  embraces  all  the  cases  that  occur, 
namely,  constancy  of  connexion  or  of  relation.  Substance, 
again,  or  matter,  is  not  anything  unconditionally  constant. 
What  we  call  matter  is  a  combination  of  the  elements  or 
sensations  according  to  certain  laws.  The  sensations  con- 
nected with  the  different  sense-organs  of  a  particular  man 
are  dependent  on  one  another  according  to  laws,  as  are 
the  sensations  of  different  men.  It  is  in  this  that  matter 
consists.  The  older  generation,  especially  the  physicists 
and  chemists,  will  be  alarmed  by  this  proposal  not  to  treat 
matter  as  something  absolutely  constant,  but  to  take  as 
constant,  instead,  a  fixed  law  of  connexion  among  elements 
which  in  themselves  seem  extremely  unstable.  Even 
younger  minds  may  find  this  conception  difficult ;  but  the 
view  is  inevitable,  though  I  myself  at  one  time  went  through 
a  great  struggle  in  order  to  arrive  at  it.  We  shall  have  to  make 
up  our  minds  to  some  such  radical  change  in  the  method  of 
our  thought,  if  we  want  to  escape  the  alternative  of  perpetu- 
ally recurring  helplessness  in  the  face  of  these  questions. 

There  can  be  no  question  of  abolishing  from  ordinary 
everyday  use  the  vulgar  conception  of  matter  which  has 
been  instinctively  developed  for  this  purpose.  Moreover, 
all  our  concepts  of  physical  measurement  can  be  maintained, 


332        THE  ANALYSIS  OF  SENSATIONS 

only  receiving  such  critical  elucidation  as  I  have  tried  to 
carry  out  for  mechanics,  heat,  electricity,  etc.  Purely 
empirical  concepts  here  take  the  place  of  metaphysical. 
But  science  suffers  no  loss  when  a  "  matter,"  which  is  a 
rigid,  sterile,  constant,  unknown  Something,  is  replaced  by 
a  constant  law,  of  which  the  details  are  still  capable  of 
further  explanation  by  means  of  physico-physiological  re- 
search. In  doing  this  our  object  is  not  to  create  a  new 
philosophy  or  metaphysics,  but  to  promote  the  efforts, 
which  the  positive  sciences  are  at  this  moment  making, 
towards  mutual  accommodation. 


*$• 

The  propositions  of  natural  science  express  only  such 
constancies  of  connexion  as :  "  The  tadpole  turns  into  a 
frog.  Chlorate  of  sodium  makes  its  appearance  in  the  form 
of  cubes.  Rays  of  light  are  rectilinear.  Bodies  fall  with  an 
acceleration  of  9*81  (m/sec2)."  When  these  constancies  are 
expressed  in  concepts,  we  call  them  laws.  Force  (in  the 
mechanical  sense)  is  likewise  merely  a  constancy  of  con- 
nexion. When  I  say  that  a  body  A  exerts  a  force  on  a  body 
B,  I  mean  that  B,  on  coming  into  contraposition  with  A,  is 
immediately  affected  by  a  certain  acceleration  with  respect 
to  A. 

The  singular  illusion,  that  the  substance  A  is  the  abso- 
lutely constant  vehicle  of  a  force  which  takes  effect  immedi- 
ately on  j#'s  being  contraposed  to  At  is  easily  removed.  If 
we,  or  more  exactly  speaking,  our  sense-organs,  be  put  in 
the  place  of  B,  here  a  condition  intervenes,  which,  seeing 
that  it  is  possible  at  any  time  to  fulfil  it,  is  invariably 


THE  ANALYSIS  OF  SENSATIONS        333 

disregarded,  and  thus  A  appears  to  us  absolutely  constant. 
Similarly,  a  magnet,  which  we  see  as  often  as  we  care  to 
look  in  its  direction,  appears  to  us  the  constant  vehicle  of  a 
magnetic  force,  which  becomes  operative  only  upon  being 
brought  near  to  a  particle  of  iron,  which  we  cannot,  with- 
out noticing  the  fact,  disregard  as  easily  as  we  can  ourselves.1 
The  phrases,  "  No  matter  without  force,  no  force  without 
matter,"  which  are  but  abortive  attempts  to  remove  a  self- 
incurred  contradiction,  become  superfluous  when  we  re- 
cognize only  constancies  of  connexion. 


1 6. 

Given  a  sufficient  constancy  of  environment,  there  is 
developed  a  corresponding  constancy  of  thought.  By  virtue 
of  this  constancy  our  thoughts  are  spontaneously  impelled 
to  complete  the  half-observed  facts.  This  impulse  towards 
completion  is  not  prompted  by  the  individual  facts  as 
observed  at  the  time ;  nor  is  it  intentionally  created ;  but 
we  find  it  operative  in  ourselves  entirely  without  our  personal 
intervention.  It  confronts  us  like  a  power  from  without, 
yet  as  a  power  which  continually  accompanies  and  assists 
us,  as  a  thing  of  which  we  stand  in  need,  in  order  to 

1  To  the  child  everything  appears  substantial,  for  the  perception  of 
which  only  his  senses  are  necessary.  The  child  asks  where  the  shadow, 
where  the  extinguished  light  goes  to.  He  will  not  allow  the  electrical 
machine  to  be  turned  any  great  length  of  time  for  fear  of  exhausting 
the  supply  of  sparks,  etc. — A  boy  of  less  than  a  year  old  wanted,  when 
his  father  whistled  a  tune,  to  catch  the  notes  from  his  lips.  Even  with 
older  children  we  find  the  attempt  to  snatch  at  coloured  after-images, 
etc.  Only  upon  noting  conditions  of  a  fact  that  are  outside  ourselves 
does  the  impression  of  substantiality  disappear.  The  history  of  the 
theory  of  heat  is  very  instructive  in  this  connexion. 


334        THE  ANALYSIS  OF  SENSATIONS 

supplement  the  facts.  Although  it  is  developed  by  experi- 
ence, it  contains  more  than  is  contained  in  the  single 
experience.  The  impulse  in  a  certain  measure  enriches  the 
single  fact.  Through  it  the  fact  is  more  to  us.  With  this 
impulse  we  have  always  a  larger  portion  of  nature  in  our 
field  of  vision,  than  the  inexperienced  man  has  with  the 
single  fact  alone.  For  the  human  being,  with  his  thoughts 
and  his  impulses,  is  himself  merely  a  piece  of  nature,  which 
is  added  to  the  single  fact.  This  impulse,  however,  can  lay 
no  claim  to  infallibility,  and  there  exists  no  necessity  com- 
pelling the  facts  to  correspond  to  it.  Our  confidence  in  it 
rests  entirely  upon  the  supposition,  which  has  been  sub- 
stantiated by  numerous  trials,  of  the  sufficiency  of  our 
mental  adaptation, — a  supposition,  however,  which  must  be 
prepared  to  be  contradicted  at  any  moment. 

Not  all  our  ideas  representing  facts  have  the  same 
constancy.  Whenever  we  have  a  special  interest  in  the 
representation  of  facts,  we  endeavour  to  support  and  cor- 
roborate ideas  of  lesser  constancy  by  ideas  of  greater 
constancy,  or  to  replace  them  by  the  latter.  Thus  Newton 
conceived  the  planets  as  projectiles,  although  Kepler's  laws 
were  already  well  known,  and  the  tides  as  attracted  by  the 
moon,  although  the  facts  of  their  movement  had  long  been 
ascertained.  We  do  not  think  that  we  understand  the 
suction  of  a  pump,  or  the  flowing  of  a  siphon,  until  we  have 
mentally  added  the  pressure  of  the  air  as  holding  the  chain 
of  particles  together.  Similarly  we  seek  to  conceive  electrical, 
optical,  and  thermal  processes  as  mechanical  processes. 
This  need  of  the  support  of  weaker  thoughts  by  stronger 
thoughts  is  also  called  the  need  of  causality,  and  is  the 
moving  spring  of  all  scientific  explanations.  We  naturally 


THE  ANALYSIS  OF  SENSATIONS        335 

prefer,  as  the  foundation  of  this  process,  the  strongest  and 
most  thoroughly  tested  thoughts,  and  these  are  given  us  by 
our  much  exercised  mechanical  functions,  which  we  may 
test  anew  at  any  moment  without  many  or  cumbersome 
appliances.  Hence  the  authority  of  mechanical  explanations, 
especially  those  by  pressure  and  impact.  A  corresponding 
and  still  higher  authority  attaches  to  mathematical  thoughts, 
for  in  their  development  we  stand  in  need  of  no  extraneous 
means  whatever,  but,  on  the  contrary,  invariably  carry  most 
of  the  material  for  experimenting  about  with  us.  But  if  we 
are  once  apprised  of  this,  the  need  of  mechanical  explana- 
tions is  appreciably  weakened.1 

I  have  already  often  pointed  out  that  a  so-called  "  causal " 
explanation,  also,  is  nothing  more  than  the  statement  or 
description  of  an  actual  fact  or  of  a  connexion  between  facts, 
and  I  might  here  simply  refer  to  the  detailed  discussions 
in  my  Theory  of  Heat  and  my  Popular  Lectures.  But,  as 
people  who  have  not  made  a  special  study  of  physics  always 
believe  that  they  broaden  the  basis  and  increase  the 
profundity  of  their  thought  if  they  assume  a  fundamental 
difference  between  a  scientific  description  (for  instance,  of 
the  development  of  an  embryo)  and  a  physical  explanation, 

1  Physical  experiences  other  than  mechanical  may  approach  to  the 
value  of  mechanical  experiences  as  they  become  more  familiar.  In  my 
opinion  Strieker  has  advanced  a  correct  and  important  view  in  bringing 
causality  into  connexion  with  the  will  (Studien  tiber  die  Assoziation  der 
Vorstellungen.)  Vienna,  1883).  When  I  was  a  young  lecturer  in  1861, 1 
myself  advocated  with  great  warmth  and  one-sidedness  (in  the  exposition 
of  Mill's  method  of  difference)  the  view  subsequently  expressed  by 
Strieker.  And  the  idea  has  never  quite  left  me  (cp.,  for  example,  my 
Science  of  Mechanics,  English  trans.,  pp.  84,  304,  485.)  However,  I 
am  at  present  of  the  opinion,  as  the  above  discussion  shews,  that  this 
question  is  not  so  simple,  and  must  be  looked  at  from  several  sides, 
(Cp.  Warmelehre,  2nd  ed.,  1900,  p.  432.) 


336        THE  ANALYSIS  OF  SENSATIONS 

I  may  perhaps  be  allowed  to  add  a  few  more  words  on  the 
subject.  When  we  describe  the  growth  of  a  plant,  we 
notice  that  there  comes  into  play  such  an  immense  variety 
of  circumstances  varying  from  one  case  to  another,  that  it 
is  only  in  the  broader  features  at  most  that  our  description 
can  hope  to  apply  universally,  while  as  regards  the  minuter 
details  it  can  only  be  accurate  for  the  individual  case. 
This  is  exactly  what  happens  in  physics  when  the  circum- 
stances are  at  all  complicated;  the  only  difference  being 
that  the  circumstances  are  generally  simpler  and  better 
known.  That  is  why  it  is  easier  for  us  in  physics  to 
separate  out  the  circumstances  experimentally,  and  intel- 
lectually too,  by  means  of  abstraction.  Schematization  is 
easier.  For  the  astronomers  of  antiquity,  to  describe  the 
motion  of  the  planets  was  a  task  analogous  to  what  the 
description  of  a  plant's  development  is  for  a  modern 
botanist.  The  discovery  of  Kepler's  laws  depends  upon 
a  fortunate  and  fairly  crude  schematization.  The  more 
closely  we  consider  a  planet,  the  more  individual  does  its 
movement  become,  and  the  less  exactly  does  it  follow 
Kepler's  laws.  Speaking  strictly,  all  the  planets  move 
differently,  and  the  same  planet  moves  differently  at 
different  times.  Now,  when  Newton  gives  a  "  causal 
explanation  "  of  the  planetary  motions  by  shewing  that  one 
particle  of  mass  m  acquires  through  another  particle  mf  the 

acceleration  <p  =  -^,  and  that  the  accelerations  deter- 
mined in  the  first  particle  by  different  particles  are  summed 
geometrically,  he  is  only  pointing  out  or  describing  facts, 
which,  although  by  a  roundabout  path,  yet  have  been 
reached  by  observation.  Let  us  consider  what  the  process 


THE  ANALYSIS  OF  SENSATIONS        337 

is.  The  circumstances  determining  the  planetary  motions 
are  first  of  all  isolated  from  one  another,  that  is  to  say,  the 
individual  particles  of  mass  and  their  distances  from  one 
another.  The  relation  between  two  particles  of  mass  is 
very  simple,  and  we  think  that  we  know  all  the  circum- 
stances, mass  and  distance,  that  determine  this  relation. 
If  we  have  a  description  which  has  been  found  to  be 
correct  for  a  few  cases,  we  extend  it  beyond  the  limits  of 
experience  and  assume  it  to  be  universally  correct,  at  the 
same  time  disregarding  the  possibility  of  any  disturbance 
from  an  unknown  and  alien  cause ;  in  this,  indeed,  we  may 
be  mistaken,  as  we  should  be,  for  instance,  if  gravity  were 
to  turn  out  to  be  transferred  through  a  medium  and  to 
require  time  for  its  transference.  The  modification  of  the 
relation  is  equally  simple,  as  was  pointed  out,  when  to  two 
particles  a  third  is  added,  and  to  these  a  fourth,  and  so  on. 
Thus  Newton's  description  is  not,  in  fact,  the  description  of 
an  individual  case ;  it  is  a  description  in  terms  of  elements. 
Newton,  in  describing  the  way  in  which  the  elements  of 
mass  are  related  to  one  another  in  the  elements  of  time, 
indicates  to  us  how  we  can  describe  in  terms  of  the  elements 
any  individual  case  we  like,  according  to  his  pattern.  It  is 
just  the  same  with  all  the  other  cases  that  theoretical  physics 
has  mastered.  But  this  does  not  mean  that  the  essence  of 
the  description  is  changed  in  any  way.  What  we  have  to  do 
with,  is  a  general  description  in  terms  of  elements.  If  we  may 
remain  satisfied  with  a  representation  of  the  phenomena  by 
means  of  differential  equations, — a  view  which  I  long  ago 
recommended  (Mechanik,  1883,  4tn  ed»,  I9OI>  P-  53°))  and 
which  seems  to  be  coming  more  and  more  into  favor, — 
this  actually  amounts  to  the  recognition  that  explanation 


338        THE  ANALYSIS  OF  SENSATIONS 

is  nothing  more  than  a  description  in  terms  of  elements. 
Every  particular  case  can  then  be  put  together  out  of  spatial 
and  temporal  elements,  the  relations  between  which  are 
described  by  equations. 


It  was  said  above  that  man  himself  is  a  fragment  of 
nature.  Let  me  illustrate  this  by  an  example.  For  the 
chemist  a  substance  may  be  sufficiently  characterized  merely 
by  his  sensations.  In  this  case  the  chemist  himself  sup- 
plies, by  inner  means,  the  whole  wealth  of  fact  necessary 
to  the  determination  of  his  course  of  thought.  But,  in 
other  cases,  recourse  to  reaction  by  the  help  of  external 
means  may  be  necessary.  When  an  electric  current  flows 
round  a  magnetic  needle  situated  in  its  plane,  the  north 
pole  of  the  needle  is  deflected  to  my  left,  if  I  imagine 
myself  as  Ampere's  swimmer  in  the  current.  I  enrich  the 
fact  (current  and  needle)  which  is  insufficient  in  itself  to 
define  the  direction  of  my  thought,  by  introducing  myself 
into  the  experiment  by  an  inner  reaction.  I  may  likewise 
lay  my  watch  in  the  plane  of  the  circuit,  so  that  the  hand 
moves  in  the  direction  of  the  current.  Then  the  south 
pole  falls  in  front  of,  the  north  pole  behind  the  dial.  Or 
I  may  make  ^of  the  circuit  traversed  by  the  current  a  sun- 
dial (on  the  plan  of  which  the  watch  in  fact  was  modelled  1), 
so  arranging  it  that  the  shadow  follows  the  current. 
In  this  case  the  north  pole  will  move  towards  the 
shadowed  side  of  the  plane  of  the  current.  The  two 
last-mentioned  reactions  are  outward  reactions.  The 

1  By  the  direction  in  which  its  hands  move  the  watch  proclaims  its 
descent  from  the  sun-dial  and  its  discovery  in  the  northern  hemisphere. 


THE  ANALYSIS  OF  SENSATIONS        339 

two  species  of  reactions  could  not  be  made  use  of  indis- 
criminately if  a  chasm  existed  between  myself  and  the 
world.  Nature  is  a  single  whole.  The  fact  that  the  two 
species  of  reaction  are  not  known  in  all  cases,  and  that 
frequently  the  observer  appears  to  be  entirely  without  in- 
fluence, proves  nothing  against  the  view  advanced. 

Right  and  left  appear  to  us  to  be  similar,  in  contrast  to 
before  and  behind,  and  to  above  and  below.  Yet  it  is 
certain  that  they  are  only  different  sensations,  overwhelmed 
by  stronger  similar  sensations.  The  space  of  sensation  thus 
has  three  strongly  marked  and  essentially  different  directions. 
From  a  metrical  point  of  view  all  directions  of  geometrical 
space  are  identical.  Our  immediate  sensation  represents 
symmetrical  shapes  as  equivalent ;  but  in  physical  respects 
they  are  by  no  means  equivalent.  Physical  space  also  has 
three  essentially  different  directions,  which  are  most  clearly 
manifested  in  a  triclinal  medium,  in  the  behaviour  of  an 
electro-magnetic  element.  The  same  physical  properties 
appear  also  in  our  own  body,  which  is  the  reason  why  our 
bodies  can  be  used  as  reagents  in  physical  problems.  If 
we  had  an  exact  physiological  knowledge  of  an  element  of 
our  bodies,  we  should  thereby  have  laid,  in  all  essentials, 
the  foundation  of  our  understanding  of  the  physical 
universe.  (Cp.  p.  100.) 

[8. 

I  have  repeatedly  emphasized  the  unity  of  the  physical 
and  the  psychical,  but  it  is  worth  while  to  consider  this 
unity  once  more  in  one  of  its  special  aspects.  Our  psychical 
life,  in  so  far  as  we  mean  by  that  term  our  presentations, 
seems  to  be  perfectly  independent  of  physical  processes ; 


340        THE  ANALYSIS  OF  SENSATIONS 

it  seems  to  be  a  world  in  itself,  with  freer  laws  of  its  own, 
laws  that  are  of  a  different  order.  But  it  is  certain  that 
this  is  a  mere  illusion,  caused  by  the  fact  that  only  a  very 
minute  part  of  the  traces  of  physical  processes  ever  comes 
to  life  in  our  presentations.  The  circumstances  determining 
this  fragment  are  much  too  complicated  to  grasp,  so  that 
it  is  impossible  to  lay  down  any  precise  rule  for  its  occur- 
rence. In  order  to  determine  what  thoughts  a  physicist, 
for  instance,  will  connect  with  the  observation  of  a  particular 
optical  fact,  we  should  have  to  know  the  previous  events 
of  his  life,  the  force  of  the  impressions  which  they  have 
left  behind  them,  and  the  facts  of  the  development  of 
general  and  technical  culture  by  which  he  has  been  influ- 
enced ;  and  finally  we  should  have  to  be  in  a  position  to 
take  into  account  his  mental  disposition  at  the  moment. 
To  do  all  this,  it  would  be  necessary  to  enlist  as  an  auxiliary 
the  whole  of  physics,  in  its  widest  sense,  and  at  an  un- 
attainably  high  stage  of  development.1 

Let  us  now  consider  the  other  side  of  the  picture.  A 
physical  fact,  which  we  experience  for  the  first  time,  is 
strange  to  us.  If  it  happened  in  some  quite  different  way 
from  that  in  which  it  actually  happens,  it  would  not  thereby 
be  any  more  puzzling.  The  way  in  which  it  occurs  appears 
to  us  not  to  be  determined  by  anything,  least  of  all  to  be 
uniquely  determined.  What  it  is  that  invests  the  way  in 
which  a  physical  fact  occurs  with  the  character  of  deter- 
minateness,  can  only  be  understood  from  our  psychical 

1  Thus,  although  my  ideal  of  psychology  is  that  it  should  be  purely 
physiological,  I  should  nevertheless  think  it  a  great  mistake  to  reject 
so-called  "introspective"  psychology  entirely.  For  self-observation 
is  not  only  an  important  means,  but  in  many  cases  is  the  only  means 
of  obtaining  information  as  to  fundamental  facts. 


THE  ANALYSIS  OF  SENSATIONS        341 

development.  The  presentational  part  of  our  mental  life 
is  the  agent  which  first  draws  the  fact  forth  from  its  isola- 
tion, brings  it  into  contact  with  an  abundance  of  other 
facts,  and  then  invests  it  with  determinateness,  in  virtue  of 
the  necessity  for  agreement  with  those  other  facts  and  for 
he  exclusion  of  contradiction.  The  science  of  psychology  is 
auxiliary  to  physics.  The  two  mutually  support  one  another, 
and  it  is  only  when  they  are  united  that  a  complete  science  is 
formed.  From  our  standpoint,  the  antithesis  of  subject  and 
object,  in  the  ordinary  sense,  does  not  exist.  The  question 
as  to  the  greater  or  less  degree  of  precision  with  which  pre- 
sentations copy  the  facts,  is,  like  every  other  question,  a 
problem  of  natural  science. 

19. 

Whenever  it  happens,  in  a  complexus  of  elements,  that 
some  of  the  elements  are  replaced  by  others,  then  a  con- 
stancy of  connexion  of  one  kind  becomes  a  different  kind. 
In  such  cases  it  is  desirable  to  discover  a  constancy  which 
survives  this  change.  J.  R.  Mayer  was  the  first  to  feel  this 
need,  and  satisfied  it  by  enunciating  his  concept  of  "force," 
which  corresponds  to  the  technical  mechanical  concept  of 
"work"  (Poncelet),  or  more  exactly  to  the  more  general 
concept  of  "  energy  "  (Young).  Mayer  conceives  this  force 
(or  energy)  as  something  absolutely  constant  (as  a  store  of 
something,  as  a  material),  thus  harking  back  to  the  most 
stubborn  intuitive  notions.  We  perceive,  from  Mayer's 
struggle  with  expressions,  and  with  general  philosophical 
phrases  (noticeable  in  the  first  and  second  of  his  treatises), 
that  he  at  first  felt  instinctively  and  intuitively  the  urgent 
need  of  such  a  concept.  But  his  great  achievement  was 


342    H  THE  ANALYSIS  OF  SENSATIONS 

accomplished  only  by  his  adapting  the  existing  physical 
concepts  to  the  requirements  of  the  facts  as  well  as  to  his 
needs.1 


20. 

When  the  adaptation  is  adequate,  the  facts  are  spon- 
taneously reproduced  by  the  thoughts,  and  incompletely 
given  facts  are  completed.  Physics  can  act  only  as  a 
quantitative  norm  regulating  and  giving  a  more  precise 
conformation  to  the  spontaneously  flowing  thoughts, 
suitably  to  practical  or  scientific  needs.  When  I  see  a 
body  thrown  horizontally,  the  intuitive  picture  of  a  pro- 
jectile in  motion  may  rise  before  my  mind.  But  the 
artilleryman  or  the  physicist  requires  more.  He  must  know, 
for  example,  that  if  on  applying  the  measuring-rod  M  to  the 
horizontal  abscissae  of  the  projectile's  path,  he  can  count  to 
i,  2,  3,  4  .  .  .  .,  he  must,  on  applying  the  measure  M'  to 
the  vertical  ordinates,  also  count  to  i,  4,  9,  16  .  .  .  .  in 
order  to  reach  a  point  of  the  path.  The  function  of  physics 
consists,  therefore,  in  teaching  that  a  fact  which,  on  a 
definite  reaction  R  yields  a  sensory  mark  JE,  also  yields,  on 
the  giving  of  a  different  reaction  J?',  a  second  sensory  mark 
E '.  By  this  means  it  is  possible  to  supply  more  exactly 
the  deficiencies  of  incompletely  given  facts. 

The  introduction  into  physics  of  the  universally  compar- 
able, or  so-called  "  absolute  "  measurements, — the  reduction 
of  all  physical  measurements  to  such  units  as  the  centimetre, 
the  gramme,  and  the  second  (length,  mass  and  time), — has 
one  peculiar  result.  There  exists  in  any  case  a  tendency  to 

1  Cp.  Prinzipien  der  Warmelehre,  2nd  ed.,  1900. 


THE  ANALYSIS  OF  SENSATIONS        343 

regard  anything  that  can  be  physically  grasped  and  measured, 
anything  that  can  be  stated  in  such  a  way  as  to  become 
common  property,  as  "objective"  and  "real,"  in  contrast  to 
the  subjective  sensations ;  and  the  absolute  measures  appear 
to  give  some  support  to  this  opinion,  and  to  supply  it  with  a 
psychological,  if  not  with  a  logical,  motive.  It  looks  as  if  what 
we  call  "sensations"  in  the  familiar  sense,  were  something 
quite  superfluous  in  physics.  Indeed,  if  we  look  closer,  the 
system  of  units  of  measurement  can  be  still  further  simplified. 
For  the  numerical  measurement  of  mass  is  given  by  a  ratio 
of  accelerations,  and  measurement  of  time  can  be  reduced 
to  measurement  of  angles  or  lengths  of  arcs.  Consequently 
measurement  of  lengths  is  the  foundation  of  all  measure- 
ments. But  we  do  not  measure  mere  space;  we  require 
a  material  standard  of  measurement,  and  with  this  the 
whole  system  of  manifold  sensations  is  brought  back 
again.  It  is  only  intuitional  sense-presentations  that  can 
lead  to  the  formulation  of  the  equations  of  physics,  and  it  is 
precisely  in  such  presentations  that  the  interpretation  of 
these  equations  consists.  Thus,  though  the  equations  only 
contain  spatial  numerical  measurements,  these  measure- 
ments, also,  are  merely  the  ordering  principle  which  tells  us 
out  of  what  members  of  the  series  of  sensational  elements 
we  have  to  construct  our  picture  of  the  world. 


21. 

I  have  elsewhere1  shewn  that  quantitative  enunciations 
are  only  distinguished  from  qualitative  by  the  fact  that  the 
former   have  reference   to   a  continuum  of  homogeneous 
1  See  Prinzipien  der  Wdrmelehre,  pp.  438,  459. 


344        THE  ANALYSIS  OF  SENSATIONS 

cases.  On  this  view,  the  advantageous  employment  of 
equations  for  purposes  of  description  would  only  be  possible 
within  a  very  limited  field.  There  is,  however,  some  pros- 
pect of  enlarging  this  field  by  successive  steps  without  any 
limit.  This  would  be  done  in  the  following  way.  All 
possible  optical  sensations,  though  they  cannot  be 
measured,  can  be  characterized  and  catalogued  by  means 
of  numbers  on  psycho-physical  methods.  Thus  any  optical 
experience  can  be  described  by  representing,  by  means  of 
equations,  the  values  of  these  numerical  characteristics  as 
dependent  on  the  spatial  and  temporal  co-ordinates,  and  on 
one  another.  And  we  shall  have  to  hold  that  a  result  the 
same  in  principle  can  be  obtained  in  the  fields  of  the  other 
senses  also.  Thus  it  is  possible  to  assign  a  perfectly  precise 
meaning  to  the  expression  used  on  p.  45  above. 


22. 

The  ascertainment  of  the  dependence  of  the  elements 
A  B  C  on  one  another,  K  L  M being  disregarded,  is  the  task 
of  natural  science,  or  of  physics  in  its  broadest  sense.  But, 
in  reality,  the  A  B  C's  are  always  also  dependent  on  K  L  M. 
There  are  always  equations  of  the  form  f(A  B  C  .  .  . 
KL  Mt  .  .  .)=  O.  Now  since  many  different  observers 
K  L  M  .  .  .  ,  K'  Lr  M'  .  .  .  ,  K"  L"  M"  .  .  .  are  in- 
volved, we  succeed  in  eliminating  the  accidental  influence 
of  the  variation  of  K  L  M,  etc.,  and  we  thus  obtain  only  the 
element  that  can  be  stated  as  common  property,  namely  the 
pure  dependence  of  the  A  B  C's  on  one  another.  In  this 
process  the  KL  M  .  .  .,  Kf  L'  M'  .  .  .,  are  treated  like 
physical  instruments,  each  with  its  peculiarities,  its  special 


THE  ANALYSIS  OF  SENSATIONS        345 

constants,  and  so  forth,  from  which  the  results,  as  finally  in- 
dicated, have  to  be  set  free.  But  if  it  is  a  question  merely 
of  the  temporal  connexion  of  one  quantitative  reaction  with 
other  quantitative  reactions,  as  in  the  above  dynamical 
example,  the  matter  is  then  still  simpler.  Everything  then 
turns  on  the  ascertainment  of  equality  or  identity  of  the 
A  B  C's  under  like  circumstances, — that  is  to  say,  under  like 
K  L  M\ — which  comes  to  saying  that  everything  turns 
merely  on  the  ascertainment  of  spatial  identities.  The 
kind  of  quality  of  the  sensations  is  now  indifferent ;  it  is 
their  equality  that  is  alone  decisive.  And  now  a  single 
individual  suffices  to  fix  relations  of  dependence  which  are 
valid  for  all  individuals.  Thus  from  this  point  onwards  we 
have  obtained  a  safe  basis  for  the  whole  field  of  scientific 
research, — a  fact  which  inures  to  the  advantage  of  psycho- 
physiology  as  well. 

23- 

The  space  of  the  geometrician  is  by  no  means  merely  the 
system  of  space-sensations  (the  senses  of  sight  and  touch), 
but  consists  rather  of  a  body  of  conceptually  idealized  and 
formulated  physical  experiences,  having  the  space-sensations 
as  their  point  of  departure.  In  the  very  fact  of  the  geome- 
trician's regarding  his  space  as  being  of  the  same  nature 
at  all  points  and  in  all  directions,  he  goes  far  beyond  the 
space  given  to  sight  and  touch,  which  by  no  means  possesses 
this  simple  property  (pp.  1 68,  1 8 1 ,  sqq.).  Without  experience 
in  physics  the  geometrician  would  never  have  reached  this 
conception.  The  fundamental  propositions  of  geometry 
have,  as  a  fact,  been  acquired  wholly  by  means  of  physical 
experiences,  by  the  superposition  of  measures  of  length 


346        THE  ANALYSIS  OF  SENSATIONS 

and  of  angles,  by  the  application  of  rigid  bodies  to  one 
another.  Without  propositions  of  congruence,  no  geometry. 
Apart  from  the  fact  that  spatial  images  would  not  be  pro- 
duced in  us  without  physical  experience,  we  should,  even 
granting  their  existence,  never  be  able  to  apply  them  to  one 
another  and  to  test  their  congruence.  When  we  feel  com- 
pelled to  imagine  an  isosceles  triangle  as  having  equal  angles 
at  its  base,  our  compulsion  is  due  to  the  remembrance  of 
powerful  past  experiences.  If  the  proposition  had  its 
source  in  "pure  intuition,"  there  would  be  no  necessity  for 
learning  it.  That  discoveries  may  be  made  by  sheer  power 
of  geometrical  imagination,  and  are  so  made  daily,  merely 
proves  that  the  memory  of  a  given  experience  can  reveal  to 
the  mind  features  which  in  the  original  observation  escaped 
unnoticed  ;  just  as  in  the  after-image  of  a  bright  lamp,  new 
and  previously  unseen  details  may  be  discovered.  Even  the 
theory  of  numbers  must  be  looked  at  in  some  such  manner ; 
its  fundamental  propositions  can  hardly  be  viewed  as  en- 
tirely independent  of  physical  experience. 

The  cogency  of  geometry  (and  of  all  mathematics)  is  due,  not 
to  the  fact  that  its  theories  are  arrived  at  by  some  peculiar  kind 
of  knowledge,  but  only  to  the  fact  that  its  empirical  material, 
which  is  particularly  convenient  and  handy,  has  been  put  to 
the  test  very  often,  and  can  be  put  to  the  test  again  at  any 
moment.  Moreover,  the  province  of  space-experience  is  far 
more  limited  than  that  of  the  whole  of  experience.  The  con- 
viction of  having  in  all  essentials  exhausted  this  limited  pro- 
vince soon  arises  and  produces  the  necessary  self-confidence.1 

1  Cp-  Wdrmelehre,  p. 455  ;  Meinong,  Hume-Studien,  Vienna,  1877  ; 
Zindler,  Beitr&ge  ztir  Theorie  der  mathematischen  Erkenntnisy 
Vienna,  1889. 


THE  ANALYSIS  OF  SENSATIONS        347 


24. 

A  self-confidence  similar  to  that  of  the  geometrician  is 
doubtless  also  possessed  by  the  composer  and  the  decora- 
tive painter,  who  have  both  gained,  the  former  in  the 
domain  of  sensations  of  tone,  the  latter  in  that  of  sensations 
of  color,  a  broad  and  rich  experience.  To  the  one  no 
space-figure  will  occur  the  elements  of  which  are  not  well 
known  to  him,  and  the  two  others  will  meet  with  no  new 
combinations  of  tone  or  of  color  that  are  unfamiliar  to 
them.  But  the  inexperienced  beginner  in  geometry  will  be 
no  less  surprised  and  disappointed  by  the  results  of  his 
activity  than  the  young  musician  or  decorator. 

The  mathematician,  the  composer,  the  decorator,  and 
the  student  of  natural  science,  when  indulging  in  specula- 
tion, pursue  quite  analogous  modes  of  procedure,  despite 
the  differences  of  their  materials  and  aims.  The  mathe- 
matician, it  is  true,  owing  to  his  more  limited  material,  has 
the  advantage  of  the  others  as  regards  the  certainty  of  his 
procedure ;  while  the  latter  for  the  opposite  reason  is  at  a 
disadvantage  as  compared  with  the  others. 


25- 

The  distinction  between  physiological  and  geometrical 
space  has  proved  to  be  unavoidable.  But  while  geome- 
trical insight  is  obtained  by  the  spatial  comparison  of  bodies 
with  one  another,  time  also  cannot  be  left  out  of  considera- 
tion, since  it  is  impossible,  in  making  such  comparisons,  to 
disregard  the  translation  of  bodies.  Space  and  time  stand 


348        THE  ANALYSIS  OF  SENSATIONS 

in  intimate  connexion,  thereby  shewing  themselves  to  be 
relatively  independent  of  the  other  physical  elements.  This 
is  expressed  in  the  fact  that  when  bodies  move  their  other 
properties  remain  relatively  constant.  It  is  precisely  owing 
to  this  fact  that  pure  geometry  and  mechanics  are  possible. 
Space  and  time,  closely  considered,  stand,  as  regards 
physiology,  for  special  kinds  of  sensations ;  but,  as  regards 
physics,  they  stand  for  functional  dependencies  upon  one 
another  of  the  elements  characterized  by  the  sensations. 
When  the  spatial  and  temporal  physiological  indices, 
conditioned  by  the  parts  and  processes  of  our  body,  are 
compared  with  one  another  in  like  physiological  circum- 
stances, we  obtain  relations  of  dependence  of  the  physical 
elements  on  one  another, — that  is,  dependence  of  the 
elements  of  one  body  on  those  of  another,  and  dependence 
of  the  elements  of  one  process  on  those  of  another.  On  the 
basis  of  this  result  we  can  take  the  temporal  and  spatial 
determinations  in  a  purely  physical  sense.  Whatever 
coincides  with  the  smaller  part  of  a  process  which  takes 
place  continuously  in  one  direction,  is  earlier  in  time.  In 
a  homogeneously  filled  space  the  position  B  is  nearer  than 
another  position  to  the  position  A,  when  B  is  reached  by 
the  process  starting  from  A  earlier  than  the  other  position 
is  reached.  The  straight  line  is  the  class-concept  of  the 
positions  uniquely  determined  by  the  physical  relations 
between  two  points,  or  infinitely  small  bodies.  The 
position  C  is  situated  at  the  point  of  bisection  of  the 
straight  line  AB^  when,  in  homogeneous  space,  processes 
starting  from  A  and  B  reach  that  position  in  equal  times, 
and  reach  it  in  a  shorter  time  than  any  other  position  with 
which  it  shares  the  first  property. 


THE  ANALYSIS  OF  SENSATIONS        349 


26. 

The  time  of  the  physicist  does  not  coincide  with  the 
system  of  time-sensations.  When  the  physicist  wishes  to 
determine  a  period  of  time,  he  applies,  as  his  standards  of 
measurement,  identical  processes  or  processes  assumed  to 
be  identical,  such  as  vibrations  of  a  pendulum,  the  rotations 
of  the  earth,  etc.  The  fact  connected  with  the  time-sensa- 
tion is  in  this  manner  made  the  subject  of  a  reaction,  and 
the  result  of  this  reaction,  the  number  which  is  obtained, 
serves,  in  place  of  the  time-sensation,  to  determine  more 
exactly  the  subsequent  movement  of  the  thought.  In  like 
manner,  we  regulate  our  thoughts  concerning  thermal  pro- 
cesses not  according  to  the  sensation  of  warmth  which 
bodies  yield  us,  but  according  to  the  much  more  definite 
sensation  which  is  obtained  from  thermometrical  reactions 
by  simply  noting  the  height  of  the  mercury.  Usually  a 
space-sensation  (a  rotation-angle  of  the  earth,  or  the  path 
of  the  hand  on  the  dial  of  a  clock)  is  substituted  for  the 
sensation  of  time,  and  for  this,  again,  a  number  is  put. 
For  example,  if  we  represent  the  excess  of  the  temperature  of 
a  cooling  body  over  that  of  its  surroundings  by  S  =  ®T~**, 
then  t  is  this  number. 

The  relation  in  which  the  quantities  of  an  equation  stand, 
is  usually  (analytically)  a  more  general  one  than  that  which  is 
meant  to  be  represented  by  the  equation.  Thus  in  the  equa- 
tion (x/a)2  +  ( yjb)2  =  i  all  possible  values  of  x  have  an  analyti- 
cal meaning,  and  yield  corresponding  values  of  y.  But  if  the 
equation  be  used  to  represent  an  ellipse,  then  only  the  values 
of  x  <  a  and  y  <  b  have  a  geometrical  (or  real)  significance. 


350        THE  ANALYSIS  OF  SENSATIONS 

Similarly,  it  would  have  to  be  expressly  added,  if  this 
were  not  obvious,  that  the  equation  S  =  0— **  represents 
the  real  process  only  for  increasing  values  of  t. 

If  we  imagine  the  natural  course  of  different  events,  say 
the  cooling  of  one  body  and  the  free  descent  of  a  second, 
represented  by  equations  involving  time,  then  time  may  be 
eliminated  from  these  equations,  and  we  may  express,  for 
example,  the  excess  of  temperature  by  means  of  the  space 
traversed  by  the  falling  body.  Thus  viewed,  the  elements 
appear  simply  as  dependent  on  one  another.  But  the 
meaning  of  such  an  equation  would  have  to  be  more 
exactly  denned  by  adding  that  only  increasing  distances  of 
descent  or  decreasing  temperatures  are  to  be  inserted 
successively  therein. 

When  we  thus  think  of  excess  of  temperature  as  deter- 
mined by  the  space  traversed  by  a  falling  body,  the 
dependence  is  not  an  immediate  one.  On  this  point  I 
agree  with  Petzoldt.1  But  the  dependence  is  no  more 
immediate  when  we  assume  excess  of  temperature  to  be 
determined  by  the  angle  of  rotation  of  the  earth.  For  no 
one  will  believe  that  the  same  temperature- values  would 
continue  to  correspond  to  the  same  angular  values,  if  the 
earth  were  to  alter  its  velocity  of  rotation  in  consequence  of 
some  shock.  But  it  seems  to  me  to  follow  from  such  con- 
siderations that  our  postulates  are  merely  provisional,  and 
depend  upon  partial  ignorance  of  the  decisive  part  played  by 
certain  independent  variables  which  are  inaccessible  to  us. 
It  is  only  in  this  sense  that  I  would  wish  the  reference  which 
I  once  made  to  a  certain  absence  of  determination,  to  be  under- 

1  Petzoldt,  "  Das  Gesetz  der  Eindeutigkeit,"  Vierteljahrcsschrift  fur 
TV  is  sense  ha  ft  lie  he  Philosophic.  Vol.  XIX.,  pp.  146  sqq. 


THE  ANALYSIS  OF  SENSATIONS        351 

stood.1  This  view,  moreover,  is  perfectly  compatible  with  the 
postulation  of  unique  determinations,  since  such  postulates 
are  always  laid  down  on  the  assumption  of  given  circumstances, 
and  with  abstraction  from  unusual  and  unexpected  changes. 
This  way  of  looking  at  the  matter  is,  as  it  seems  to  me,  in- 
evitable, when  we  reflect  that  the  distinction  emphasized  by 
Petzoldt  between  simultaneous  and  successive  dependencies, 
holds  for  intuitional  presentation,  but  not  for  the  equations 
which  are  the  norms  regulating  presentation  quantitatively. 
The  equations  can  only  be  of  one  kind,  and  can  only  express 
simultaneous  dependencies.  Towards  indeterminism  in  the 
ordinary  sense, — the  assumption,  for  instance,  of  .freedom 
of  the  will  in  the  sense  used  by  many  philosophers  and 
theologians, — I  have  not  the  slightest  inclination. 

Time  is  not  reversible.  A  warm  body  set  in  cool  sur- 
roundings merely  cools,  and  does  not  grow  warm  again. 
With  larger,  or  later,  time-sensations  only  smaller  decreasing 
excesses  of  temperature  are  connected.  A  house  in  flames 
burns  down  but  never  builds  itself  up  again.  A  plant  does 
not  decrease  in  size  and  creep  into  the  earth,  but  grows  out 
of  it,  increasing  in  size.  The  irreversibility  of  time  reduces 
itself  to  the  fact  that  the  alterations  in  the  values  of  physical 
quantities  always  take  place  in  definite  directions.  Of  the 
two  analytical  possibilities  one  only  is  actual.  We  do  not 
need  to  see  in  this  fact  a  metaphysical  problem. 

Changes  can  only  be  determined  by  differences.  Where 
there  are  no  distinctions  there  is  no  determination.  The 
supervening  change  may  increase  the  distinctions  or  it  may 

1  Mach,  History  and  Root  of  the  Principle  of  the  Conservation  of 
Energy,  translated  by  P.  E.  B.  Jourdain,  Chicago,  Open  Court  Publish- 
ing Co.,  1911. 


352        THE  ANALYSIS  OF  SENSATIONS 

diminish  them.  But  if  the  differences  had  a  tendency  to 
increase,  change  would  go  on  endlessly  and  aimlessly. 
The  only  assumption  compatible  with  a  general  representa- 
tion of  the  universe,  or  rather  with  the  representation  of 
our  own  limited  environment,  is  that  of  a  tendency,  on  the 
whole,  to  a  diminution  of  differences.  But  if  circumstances 
that  set  up  differences  did  not  make  themselves  felt  by 
forcing  their  way  into  our  environment,  a  time  would  soon 
come  when  nothing  more  would  happen  at  all. 

Again,  we  can  conclude,  with  Petzoldt,  from  our  own 
existence  and  from  our  bodily  and  spiritual  stability,  to 
the  stability  and  to  the  uniqueness,  as  regards  determina- 
tion and  direction,  of  the  processes  of  nature.  For  not 
only  are  we  ourselves  a  fragment  of  nature  (p.  338  above), 
but  it  is  the  presence  of  these  very  properties  in  our  en- 
vironment that  determines  our  existence  and  our  thought 
(see  Popular  Scientific  Lectures,  3rd  edition,  p.  250).  But  it 
will  not  do  to  build  too  confidently  on  this  foundation,  for 
organisms  are  peculiar  fragments  of  nature,  of  very  limited 
and  moderate  stability,  which  in  point  of  fact  are  liable  to  de- 
struction, and  for  the  preservation  of  which  a  proportionately 
moderate  amount  of  stability  in  the  environment  is  sufficient. 
The  most  convenient  course  will  therefore  be  to  recognize  the 
limits  which  are  everywhere  manifestly  set  to  our  knowledge, 
and  to  regard  the  effort  towards  unique  determination  as  an 
ideal,  which,  so  far  as  may  be,  we  actualize  in  our  thought. 

I  do  not,  of  course,  regard  the  statements  which  I  wrote 
down  at  the  time  of  my  greatest  intellectual  ferment  (1871), 
as  secure  against  all  attack,  particularly  as  regards  their 
form  ;  nor  do  I  by  any  means  consider  that  Petzoldt's 
objections  are  dictated  by  a  spirit  of  captiousness.  I  hope, 


THE  ANALYSIS  OF  SENSATIONS        353 

however,  that  when  I  deal  with  the  subject  again  at  greater 
length, — for  I  have  only  been  able  to  touch  upon  it  briefly 
here, — I  shall  be  able  to  bring  about  a  full  understanding, 
without  at  the  same  time  giving  up  any  essential  part  of 
my  view.1 

1  My  recently  published  book,  Erkenntnis  undlrrtum  (1905),  contains 
further  discussions  of  the  question.     See,  in  particular,  pp.  426-440. 


XV. 

HOW  MY  VIEWS  HAVE  BEEN 
RECEIVED. 

i. 

WHEN  the  first  edition  of  this  book  was  published, 
opinions  about  it  were  greatly  divided.  But  in 
the  great  majority  of  cases,  it  was  points  of  detail  that 
found  acceptance,  in  so  far  as  the  reception  was  favorable, 
-while  the  fundamental  views  which  had  led  to  the  details 
were  for  the  most  part  rejected.  All  the  public  criticism 
that  I  have  seen  has  preserved  a  tone  of  moderation,  even 
when  it  has  been  hostile,  and,  in  its  outspokenness,  has 
been  extremely  instructive  to  me.1 

There  is  no  mistaking  the  favorable  influence  which 
the  later  publications  of  Richard  Avenarius  have  exercised 
on  the  estimation  of  my  book.  It  surely  gives  much  food 
for  thought,  when  we  find  a  professional  philosopher 

1  That  private  judgments  had  been  equally  moderate  I  should  not 
have  believed,  even  if  certain  small  indiscretions  had  not  given  me 
evidence  to  the  contrary.  A  more  than  contemptuous  judgment  of  a 
German  colleague  was  communicated  to  me  by  a  curiously  roundabout 
path — let  us  say  more  or  less  by  way  of  the  Antipodes — with  the  un- 
mistakable intention  of  giving  me  pain.  This  object,  to  be  sure,  was 
not  attained.  For  it  would  certainly  be  very  unfair  if  I  were  to  refuse 
to  others  the  right,  which  I  exercise  often  enough  myself,  of  neglecting 
work  that  I  consider  unprofitable.  To  be  sure,  I  have  never  felt  it 
necessary  to  insult  people  whose  opinions  differ  from  my  own. 

354 


THE  ANALYSIS  OF  SENSATIONS        355 

establishing  in  an  elaborate  systematic  treatise  a  position 
which,  when  taken  up  by  a  scientist,  there  has  been  a 
disposition  to  explain  away  as  the  aberration  of  a  dilettante. 
To-day  Avenarius'  pupils,  and  many  younger  inquirers  who 
have  drawn  near  to  my  position  by  paths  of  their  own, 
are  standing  at  my  side  as  allies.  Nevertheless,  all  the 
critics,  with  few  exceptions,  including  those  who  reproduce 
my  fundamental  ideas  quite  correctly  and  have  certainly 
understood  them,  cannot  help  feeling  serious  objections  to 
them.  There  is  nothing  surprising  in  this ;  for  I  make 
great  demands  on  the  plasticity  of  my  readers.  It  is  one 
thing  to  understand  an  idea  logically,  and  another  to  take 
it  up  in  a  sympathetic  spirit.  The  ordering  and  simplifying 
function  of  logic  can,  indeed,  only  begin  when  psychical 
life  is  in  an  advanced  stage  of  development  and  can 
already  boast  a  rich  store  of  instinctive  acquisitions.  Now 
it  is  scarcely  possible  to  attain  to  this  instinctive  pre-logical 
nucleus  of  acquisitions  by  logical  means.  It  is  much  more 
a  question  of  a  process  of  psychical  transformation,  which, 
as  I  found  in  my  own  case,  is  difficult  enough  even  in 
youth.  It  would  therefore  be  too  much  to  count  on 
immediate  agreement  here.  On  the  contrary,  I  am  satisfied 
to  be  merely  allowed  a  hearing  at  all,  and  to  be  listened  to 
without  prepossessions.  I  will  now,  following  the  impres- 
sions I  have  received  from  my  critics,  once  more  bring  out 
and  illustrate  those  points  of  which  the  reception  has  been 
most  strenuously  opposed.  In  doing  this,  I  shall  treat  the 
objections  that  have  been  urged  as  typical  objections,  with 
nothing  captious  or  personal  about  them,  and  I  shall  there- 
fore not  mention  any  names. 


356        THE  ANALYSIS  OF  SENSATIONS 


Unless  we  subject  ourselves  to  a  certain  compulsion,  we 
see  the  earth  as  standing  still,  and  the  sun  and  the  fixed 
stars  in  motion.  This  way  of  looking  at  the  matter  is  not 
merely  sufficient  for  ordinary  practical  purposes,  but  is  also 
the  simplest  and  most  advantageous.  But  the  opposite 
view  has  established  itself  as  the  more  convenient  for  certain 
intellectual  purposes.  Although  both  are  equally  correct 
and  equally  well-adapted  to  their  special  purpose,  the 
second  view  only  succeeded  in  gaining  acceptance  after  a 
severe  combat  with  a  power  hostile  to  science, — a  power 
which  in  this  case  was  in  alliance  with  the  instinctive 
conceptions  of  ordinary  people.  But  to  ask  that  the 
observer  should  imagine  himself  as  standing  upon  the  sun 
instead  of  upon  the  earth,  is  a  mere  trifle  in  comparison 
with  the  demand  that  he  should  consider  the  Ego  to  be 
nothing  at  all,  and  should  resolve  it  into  a  transitory 
connexion  of  changing  elements.  It  is  true  that  on  various 
sides,  the  way  has  long  been  prepared  for  this  conception.1 
We  see  such  unities  as  we  call  "  I  "  produced  by  generation 
and  vanishing  in  death.  Unless  we  indulge  ourselves  in 
the  fiction,  so  fantastic  nowadays,  that  these  unities  existed 
before  birth  in  a  latent  state,  and  will  similarly  continue  to 
exist  after  death,  we  can  only  suppose  that  they  are  just 
temporary  unities.  Psychology  and  psycho-pathology  teach 

1  Cp.  the  standpoint  of  Hume  and  Lichtenberg.  For  thousands  of 
years  past  Buddhism  has  been  approaching  this  conception  from  the 
practical  side.  Cp.  Paul  Carus,  The,  Gospel  of  Buddha,  Chicago,  1894. 
Cp.  also  the  wonderful  story  unfolded  by  the  same  writer  in  Karma,  A 
Story  of  Early  Buddhism^  Chicago,  1894. 


THE  ANALYSIS  OF  SENSATIONS        357 

us  that  the  Ego  can  grow  and  be  enriched,  can  be 
impoverished  and  shrink,  can  become  alien  to  itself,  and 
can  split  up, — in  a  word,  can  change  in  important  respects 
in  the  course  of  its  life.  In  spite  of  all  this,  the  Ego  is 
what  is  most  important  and  most  constant  for  my  instinctive 
conceptions.  It  is  the  bond  that  holds  all  my  experiences 
together,  and  the  source  of  all  my  activity.  In  just  the 
same  way,  again,  a  rigid  body  is  something  very  constant 
for  our  crude  instinctive  conceptions.  If  it  is  divided, 
dissolved,  or  chemically  combined  with  another  body,  the 
number  of  these  constancies  increases  and  diminishes. 
Then,  in  order  to  hold  fast  at  any  price  to  the  notion  that 
has  become  so  dear  to  us,  we  assume  latent  constancies, 
and  take  refuge  in  atomism.  Inasmuch  as  we  are  often 
able  to  restore  again  the  body  which  has  disappeared  or 
changed,  this  procedure  rests  upon  somewhat  better 
grounds  than  in  the  case  of  the  Ego. 

Now  in  practice  we  can  as  little  do  without  the  Ego- 
presentation  when  we  act,  as  we  can  do  without  the 
presentation  of  a  body  when  we  grasp  at  a  thing.  Physio' 
logically  we  remain  egoists  and  materialists,  just  as  we 
always  see  the  sun  rise  again.  But  theoretically  this  way 
of  looking  at  the  matter  cannot  be  maintained.  Let  us 
change  it  by  way  of  experiment.  If  in  doing  so  we  obtain 
a  glimpse  of  the  truth,  it  will  in  the  long  run  bear  practical 
fruits  as  well. 


Anyone  who  has  at  some  time  or  another  been  influenced 
by  Kant, — anyone  who  has  adopted  an  idealistic  standpoint, 
and  has  been  unable  to  get  rid  of  the  last  traces  of  the 


358        THE  ANALYSIS  OF  SENSATIONS 

notion  of  the  "thing  in  itself,"  retains  a  certain  inclination 
towards  solipsism,  which  will  appear  more  or  less  clearly. 
Having  been  through  it  in  my  early  youth,  I  know  this 
condition  of  mind  well,  and  can  easily  understand  it.  The 
philosophical  thinker  proceeds  to  make  the  single  problem 
of  the  Ego, — a  problem  which  is  in  principle  insoluble, — 
the  starting-point  for  everything  else.  The  Ego  is  some- 
thing given  to  us,  we  cannot  transcend  it  and  get  away  from 
it.  When,  therefore,  speculative  philosophers  say  "  Solipsism 
is  the  only  logically  consistent  standpoint,"  their  utterance 
is  quite  intelligible  in  view  of  their  struggle  to  reach  a 
closed,  all-inclusive,  complete  system  of  the  universe.  To 
be  sure,  we  ought  to  add  that  materialism  also  is  equally 
consistent  for  anyone  who  believes  that  matter  is  the  only 
thing  that  is  immediately  given,  and  that  cannot  be  further 
explained.  This,  indeed,  is  true  of  all  systems.  But  when 
a  man  of  science  tells  me  that  solipsism  is  the  only  con- 
sistent standpoint,  he  excites  my  astonishment.  I  will  not 
emphasize  the  fact  that  this  standpoint  is  better  suited 
to  a  fakir  who  dreams  his  life  away  in  contemplation, 
than  to  a  serious,  thoughtful  and  active  man.  But  what  I 
do  believe  is  that  the  man  of  science  who  inclines  this  way 
is  making  a  confusion  between  philosophical  and  scientific 
methods.  The  man  of  science  is  not  looking  for  a  com- 
pleted vision  of  the  universe ;  he  knows  beforehand  that  all 
his  labor  can  only  go  to  broaden  and  deepen  his  insight. 
For  him  there  is  no  problem  of  which  the  solution  would 
not  still  require  to  be  carried  deeper;  but  there  is  also 
no  problem  which  he  can  regard  as  absolutely  insoluble. 
If  it  is  impossible  for  the  time  being  to  make  any 
impression  on  a  problem,  he  solves  in  the  meanwhile 


THE  ANALYSIS  OF  SENSATIONS        359 

others  that  are  more  accessible.  If  he  then  returns  to 
the  original  problem,  it  has  generally  lost  much  of  its 
terrifying  appearance. 

No  doubt  the  Ego  is  not  exhausted,  if  we  say,  quite 
provisionally,  that  it  consists  in  a  peculiar  connexion  of  the 
elements,  as  long  as  the  nature  of  this  connexion  is  not 
investigated  in  detail.  But  the  special  problems  that  are 
relevant  here  will  not  be  solved  by  speculation  j  their  solu- 
tion will  be  found  by  the  psychologists,  physiologists,  and 
psychiatrists,  to  whom  we  already  owe  many  important 
elucidations  of  such  problems.  The  physical  substratum 
of  the  Ego,  the  body,1  will  afford  many  points  of  reference 
which  introspective  psychology  can  only  handle  in  a  very  im- 
perfect manner.  A  man  of  science  who  should  be  a  solipsist 
would  be  like  a  physicist  for  whom  the  thermometer  was 
the  fundamental  problem  of  the  universe,  because  on  any 
particular  day  he  did  not  happen  to  have  a  perfectly  clear 
understanding  of  the  influence  of  temperature  on  expansion. 
On  the  other  hand,  the  philosopher  who  is  a  solipsist  seems 
to  me  to  be  like  the  man  who  gave  up  turning  round 
because  whatever  he  saw  was  always  in  front  of  him.  As 
to  the  instinctive,  but  untenable,  splitting  up  of  the  Ego 
into  an  object  experienced  and  an  active  or  observing 
subject, — a  problem  which  has  tormented  everybody  long 
enough, — anyone  who  wishes  to  think  out  these  questions 
may  compare  pp.  25-29  above. 

1  But  what  is  in  question  here  is  not  a  transcendental,  unknowable 
Ego,  which  many  philosophers  perhaps  still  think  it  impossible  to 
eliminate  as  a  last  remnant  of  the  thing-in-itself,  although,  generally 
speaking,  they  have  risen  superior  to  that  notion  by  now. 


360        THE  ANALYSIS  OF  SENSATIONS 


Whoever  cannot  get  rid  of  the  conception  of  the  Ego  as 
a  reality  which  underlies  everything,  will  also  not  be  able 
to  avoid  drawing  a  fundamental  distinction  between  my 
sensations  and  your  sensations.     In  the  same  way,  whoever 
believes  in  the  absolute  constancy  of  a  body,  thinks  of  this 
body  as  the  single  vehicle  of  all  its  properties.     But  when 
this  silvery-white  piece  of  sodium  is  melted,  and  dissolves 
in  steam  which  looks  absolutely  different  from  the  original 
thing ;  when  the  sodium  is  divided  into  different  parts  and 
transferred   to    different   chemical   combinations,   so   that 
more,  or  even  fewer,  bodies  are  present  than  before ;  then 
our  habitual  manner  of  thought  can  only  be  preserved  by 
extremely  artificial  devices.     It  then  becomes  more  advan- 
tageous  to  regard  the  particular  properties   as  belonging 
sometimes  to  one  and  sometimes  to  another  complex,  or 
body,  and  to  substitute,  for  the  bodies  that  are  not  constant, 
the  law  which  is  constant  and  which  survives  the  change  of 
the  properties  and  of  their  connexions.     Here  again,  it  is 
making  no  small  demand,  to  ask  that  this  new  habit  of 
thought  should  be  adopted.     How  the  thinkers  of  antiquity 
would  have  protested,  if  someone  had  said  to  them,  "  Earth, 
water  and  air  are  not   constant  bodies  at  all;   what  are 
constant  are  the  modern  chemical  elements  of  which  they 
are  composed,  many  of  which  elements  cannot  be  seen, 
while  others  can  only  be  isolated  or  fixed  with  great  diffi- 
culty.    Fire  is  not  a  body  at  all,  but  a  process,"  and  so  on. 
We  are  scarcely  able  to  estimate  correctly  nowadays  the 
magnitude  of  the  change  which  lies  in  this  step.     Yet  in 


THE  ANALYSIS  OF  SENSATIONS        361 

modern  chemistry  a  further  transformation  in  this  direction 
is  being  prepared,  and  the  same  methods  of  abstraction 
lead  in  due  course  to  the  standpoint  which  is  adopted  here. 
From  the  standpoint  which  I  here  take  up  for  purposes  of 
general  orientation,  I  no  more  draw  an  essential  distinction 
between  my  sensations  and  the  sensations  of  another  person, 
than  I  regard  red  or  green  as  belonging  to  an  individual 
body.  The  same  elements  are  connected  at  different  points 
of  attachment,  namely  the  Ego's.  But  these  points  of 
attachment  are  not  anything  constant.  They  arise,  they 
perish,  and  are  incessantly  being  modified.  But  where 
there  is  no  connexion  at  a  given  moment,  there  is  also  no 
perceptible  reciprocal  influence.  Whether  it  may  or  may  not 
prove  possible  to  transfer  someone  else's  sensations  to  me  by 
means  of  nervous  connexions,  my  view  is  not  affected  one 
way  or  the  other.  The  most  familiar  facts  provide  a  sufficient 
basis  for  this  view. 


Perhaps  even  more  than  in  my  fundamental  ideas,  many 
readers  have  found  a  stumbling-block  in  what  they  took, 
erroneously  indeed,  to  be  the  general  character  of  my 
conception  of  the  universe.  And,  to  begin  with,  I  must 
say  that  anyone  who,  in  spite  of  repeated  protests  from 
myself  and  from  other  quarters,  identifies  my  view  with 
that  of  Berkeley,  is  undoubtedly  very  far  removed  from  a 
proper  appreciation  of  my  position.1  This  misconception 

1  Shall  once  again  state  the  difference  in  a  word  ?  Berkeley  regards 
the  ' '  elements "  as  conditioned  by  an  unknown  cause  external  to 
them  (God)  ;  accordingly  Kant,  in  order  to  appear  as  a  sober  realist, 
invents  the  "  thing-in-itself  "  ;  whereas,  on  the  view  which  I  advocate, 
a  dependence  of  the  "elements"  on  one  another  is  theoretically  and 


362        THE  ANALYSIS  OF  SENSATIONS 

is  no  doubt  partly  due  to  the  fact  that  my  view  was  de- 
veloped from  an  earlier  idealistic  phase,  which  has  left  on 
my  language  traces  which  are  probably  not  even  yet  entirely 
obliterated.  For,  of  all  the  approaches  to  my  standpoint, 
the  one  by  way  of  idealism  seems  to  me  the  easiest  and 
most  natural.  And  connected  with  this  is  the  fear  of 
pan-psychism,  which  at  the  same  time  seizes  my  readers. 
Many  are  the  victims  that  fall  a  prey  to  pan-psychism,  in  the 
desperate  struggle  between  a  monistic  conception  of  the  uni- 
verse and  instinctive  dualistic  prejudices.  In  my  early  youth 
I  had  to  work  through  these  tendencies  myself,  and  Avenarius 
was  still  labouring  at  them  in  his  book  of  1876.  As  regards 
these  two  points,  I  feel  it  to  be  a  piece  of  particularly  good 
fortune  that  Avenarius  has  developed  the  same  conception  of 
the  relation  between  the  physical  and  psychical  on  an  entirely 
realistic,  or,  if  the  phrase  be  preferred,  a  materialistic  founda- 
tion, so  that  I  need  do  no  more  than  refer  to  his  discussions. 


6. 

My  world  of  elements,  or  sensations,  strikes  not  only  men 
of  science,  but  also  professional  philosophers,  as  too  un- 
practically all  that  is  required.  It  seems  to  me  that,  in  the  interpreta- 
tion of  Kant,  his  very  natural  and  psychologically  intelligible  fear  of 
being  considered  fantastic,  has  not  been  sufficiently  taken  into  account. 
It  is  only  from  this  point  of  view  that  we  can  understand  how,  while 
holding  that  only  those  concepts  had  meaning  and  value  which  were 
applicable  to  a  possible  experience,  he  could  posit  a  thing  in  itself,  of 
which  no  experience  is  conceivable.  Over  against  the  particular  sensation, 
the  plain  man  and  the  man  of  science  both  set  the  thing  as  a  presentational 
complex  of  all  the  experiences,  whether  remembered  or  still  expected, 
which  are  connected  with  the  sensation  in  question  ;  and  this  procedure 
is  extremely  shrewd.  But  for  anyone  who  has  assimilated  Kant's  way 
of  thinking,  it  becomes  meaningless  at  the  limits  of  experience. 


THE  ANALYSIS  OF  SENSATIONS        363 

substantial.  When  I  treat  matter  as  a  mental  symbol 
standing  for  a  relatively  stable  complex  of  sensational 
elements,  this  is  described  as  a  conception  which  does  not 
make  enough  of  the  material  world.  The  external  world, 
it  is  felt,  is  not  adequately  expressed  as  a  sum  of  sensa- 
tions;  in  addition  to  the  actual  sensations,  we  ought  at 
least  to  bring  in  Mill's  possibilities  of  sensation.  In  reply 
to  this,  I  must  observe  that  for  me  also  the  world  is  not 
a  mere  sum  of  sensations.  Indeed,  I  speak  expressly  of 
functional  relations  of  the  elements.  But  this  conception 
not  only  makes  Mill's  "possibilities"  superfluous,  but  re- 
places them  by  something  much  more  solid,  namely  the 
mathematical  concept  of  function.  Had  I  ever  dreamt 
that  a  short,  precise  expression  would  be  so  easily  over- 
looked, and  that  a  popular  exposition  on  broad  lines 
would  have  been  more  useful,  some  such  exposition  as 
that  which  H.  Cornelius 1  has  so  admirably  given  "  on  the 
concept  of  objective  existence,"  would  have  served  my 
purpose.  In  any  case,  even  here  I  should  have  avoided 
the  expression  "possibility,"  and  should  have  substituted 
for  it  the  concept  of  function. 

From  expressions  used  in  other  quarters,  it  would  appear 
that  the  true  explanation  of  my  position  is  to  be  sought  in 
an  exaggerated  sensationalism,  and  in  a  correspondingly 
inadequate  understanding  of  the  value  of  abstraction  and 
conceptual  thought.  Now,  without  a  fairly  well-marked 
sensationalism  a  man  of  science  cannot  accomplish  much. 
But  this  does  not  prevent  him  from  forming  clear  and  pre- 
cise concepts.  On  the  contrary.  The  concepts  of  modern 

1  Psychologic  als  Erfahrungswissenschaft,  Leipzig,  1897,  p.  99,  and 
particularly  pp.  noand  in. 


364        THE  ANALYSIS  OF  SENSATIONS 

physics  will  stand  comparison,  in  point  of  precision  and 
height  of  abstraction,  with  those  of  any  other  science ; 
but  they  offer  at  the  same  time  the  advantage  that  they 
can  always  be  traced  back  with  ease  and  certainty  to  the 
sensational  elements  on  which  they  are  built  up.  For 
science  the  gulf  between  intuitional  presentation  and  con- 
ceptual thought  is  not  so  great,  and  is  not  unbridgeable. 
I  may  remark  in  passing  that  I  am  far  from  thinking 
meanly  of  the  concepts  of  physics ;  for  nearly  forty  years 
I  have  been  occupied  with  the  criticism  of  them  in  various 
ways,  and  with  greater  thoroughness  than  they  have  re- 
ceived before.  And  since  my  results  are  gradually,  after 
long  resistance,  finding  acceptance  with  physicists,  it  will 
perhaps  be  allowed  that  this  is  no  cheap  and  facile  agree- 
ment. When  the  physicist,  whose  training  has  accustomed 
him  to  having  a  kilogram  weight  pressed  into  his  hand 
with  every  definition,  gradually  expresses  himself  as 
satisfied  with  definitions  which  reduce  everything  to  a 
functional  relation  of  sensational  elements,  the  philosopher 
will  surely  not  want  to  be  even  more  of  a  physicist  than 
the  physicist.  Naturally,  however,  there  is  no  room  for 
the  necessary  working  out  of  details  in  this  sketch,  which 
is  intended  to  be  merely  a  programme  for  the  closer 
connexion  of  the  exact  sciences  with  one  another;  for 
further  information  the  reader  must  be  referred  to  my 
works  on  physics.  It  would,  indeed,  be  highly  pre- 
sumptuous of  me  to  assume  even  that  all  physicists  are 
acquainted  with  these  works,  much  more  that  they  are 
familiar  to  people  who  are  not  professional  physicists ;  yet 
it  is  partly  want  of  familiarity  with  my  works  which  has 
made  it  possible  for  me  to  be  accused,  for  instance, 


THE  ANALYSIS  OF  SENSATIONS        365 

of  having  entirely  overlooked  the  "  spontaneity "  and 
"autonomy"  of  thought.  Even  towards  bare  sensations 
our  attitude  is  not  one  of  mere  passivity;  for  sensations 
disengage  a  biological  reaction,  of  which  the  natural  con- 
tinuation is  precisely  the  adaptation  of  thought  to  facts. 
If  this  adaptation  were  immediately  and  perfectly  success- 
ful, the  process  would  ipso  facto  come  to  an  end.  But 
since  different  imperfectly  adapted  thoughts  come  into 
conflict  with  one  another,  the  biological  process  continues. 
What  I  have  called  the  adaptation  of  thoughts  to  one 
another  takes  place.  Now  I  should  really  like  to  know 
what  process  of  scientific  development,  the  logical  process 
included,  is  not  covered  by  this  statement  ?  Here  I  may 
be  permitted  to  break  off  for  the  present  these  controversial 
remarks,  in  which  I  have  only  been  forced  to  repeat  what 
I  have  frequently  said  and  have  long  been  saying. 


To  many  readers  the  universe,  as  conceived  by  me, 
seems  to  be  a  chaos,  a  hopelessly  tangled  web  of  elements, 
They  feel  the  want  of  leading  and  unifying  points  of  view. 
But  this  depends  on  a  misinterpretation  of  the  task  that  I 
have  set  myself.  All  points  of  view,  which  are  of  value 
for  the  special  sciences  and  for  the  philosophical  considera- 
tion of  the  world,  remain  capable  of  further  application, 
and  indeed,  are^  so  applied  by  me.  The  apparently 
destructive  tendency  of  the  work  is  merely  directed  against 
superfluous,  and  therefore  misleading,  additions  to  our 
concepts.  Thus  I  believe  that  the  contrasts  between  the 
psychical  and  the  physical,  and  between  subjective  and 


366        THE  ANALYSIS  OF  SENSATIONS 

objective,  have  been  correctly  reduced  by  me  to  what 
is  essential  in  them,  and  at  the  same  time  have  been 
purged  of  traditional  and  superstitious  conceptions.  And 
this  has  been  done  in  such  a  way  that  scientifically  es- 
tablished points  of  view  are  not  altered,  and  at  the  same 
time,  room  is  made  for  new  points  of  view.  I  have  no 
desire  to  set  up,  in  the  place  of  the  lamentations  of 
a  piously  whining  "  Ignorabimus,"  an  obstinately  self- 
sufficient  attitude  of  rejection  of  everything  that  is  worth 
knowing  and  that  can  be  known.  For  to  refuse  to  attempt 
answers  to  questions  that  have  been  recognized  as  meaning- 
less, is  in  no  sense  an  act  of  resignation ;  in  view  of  the 
mass  of  material  that  can  really  be  investigated,  it  is  the 
only  reasonable  course  open  to  a  man  of  science.  The 
physicist  who  refrains  from  seeking  for  the  secret  of  per- 
petual motion,  need  not  nowadays  regard  this  as  an  act  of 
resignation,  any  more  than  the  mathematician,  who  no 
longer  troubles  himself  about  the  squaring  of  the  circle, 
or  the  solution  of  equations  of  the  fifth  degree  in  closed 
algebraical  form.  So,  too,  with  more  general  philosophical 
questions  :  the  problems  are  either'solved,  or  are  recognized 
as  pointless. 

"  In  what  exactly  does  the  fallacy,  or  the  bias,  of  Mach's 
philosophical  views  consist  ?  "  This  question,  which  one  of 
my  critics  asks,  strikes  me  as  very  harmless.  For  I  am 
convinced  that  my  exposition  is  full  of  defects  in  more 
than  one  direction.  This,  indeed,  can  scarcely  be  avoided 
when  a  writer's  views  are  undergoing  a  radical  process  of 
revolution,  for  even  a  single  head  cannot  work  out  such 
a  process  completely  to  its  conclusion.  Hence,  though  I 
can  feel  these  faults,  I  cannot  put  my  finger  on  them.  If 


THE  ANALYSIS  OF  SENSATIONS        367 

I  could,  I  should  be  a  long  way  further  advanced  towards 
my  goal.  But  neither  have  I  been  able  to  obtain  a  clear 
view  of  my  faults  from  the  writings  of  my  critics.  Let  us, 
therefore,  wait  a  little  longer. 

Arguments  have  been  brought  against  my  views,  which 
have  been  fully  discussed  both  in  this  book  and  in  other 
writings  of  mine ;  but  I  do  not  state  this  fact  with  a  desire 
to  reproach  anybody.  It  must  be  a  real  torture  to  have  to 
read  everything  that  is  published,  and,  what  is  more,  to 
have  to  pass  judgment  conscientiously  and  deliberately  in 
a  brief  allotted  time.  I  have  never  discovered  in  myself 
any  taste  for  this  important  vocation,  and  consequently  I 
have  only  written  three  reviews,  all  told,  in  a  period  of  forty 
years.  So  I  do  not  grudge  it  to  the  reviewers,  that  they 
should  have  saved  themselves  a  certain  amount  of  trouble, 
even  though  it  has  been  partly  at  my  expense.  I  hope  they 
will  not  take  it  ill  on  my  part,  if  I  do  not  re-act  to  every  sally 
and  to  every  sarcasm  which  they  fancy  has  hit  its  mark. 

Honigswald,  however,  has  subsequently  devoted  a  book 
to  my  standpoint  (Zur  Kritik  der  Machschen  Philosophic, 
Berlin,  1903).  I  must  admit  that  he  has  taken  the  trouble 
to  read  my  books ;  nor  have  I  the  least  objection  to  make 
to  a  criticism  which  decides  that  my  position  is  incom- 
patible with  Kant's.  Not  all  philosophers  will  draw  the 
inference  that  my  position  must  therefore  be  untenable. 
My  relations  to  Kant  have  been  peculiar.  His  critical 
idealism  was,  as  I  recognize  with  the  greatest  gratitude, 
the  starting-point  of  all  my  critical  thought;  but  it  was 
impossible  for  me  to  retain  my  allegiance  to  it.  I  very 
soon  began  to  gravitate  again  towards  the  views  of  Berkeley, 
which  are  contained,  in  a  more  or  less  latent  form,  in  Kant's 


368        THE  ANALYSIS  OF  SENSATIONS 

writings.  By  studying  the  physiology  of  the  senses,  and 
by  reading  Herbart,  I  then  arrived  at  views  akin  to  those 
of  Hume,  though  at  that  time  I  was  still  unacquainted 
with  Hume  himself.  To  this  very  day  I  cannot  help 
regarding  Berkeley  and  Hume  as  far  more  logically  con- 
sistent thinkers  than  Kant.  It  is  not  the  business  of  a 
man  of  science  to  criticize  or  refute  a  philosopher  like 
Kant,  though  it  may  be  observed  in  passing  that  it  would 
no  longer  be  a  particularly  heroic  achievement  to  shew  the 
inadequacy  of  Kant's  philosophy  as  a  guide  to  modern 
scientific  research.  This  has  long  since  been  effected  by 
the  progress  that  has  been  made  in  all  departments,  in- 
cluding philosophy  itself.  When  Honigswald  enunciates  a 
number  of  general  points  of  view,  and  proceeds  to  elicit 
from  them  a  closed  philosophical  system,  he  completely 
misapprehends  the  cautiously  tentative  methods  of  ap- 
proximation employed  by  science.  The  constants  of  the 
man  of  science  are  not  absolutely  constant,  nor,  on  the 
other  hand,  do  the  changes  which  he  investigates  correspond 
to  the  limitless  flux  of  Herakleitos.  I  call  biological  aims 
11  practical,"  when  they  are  not  directed  to  pure  knowledge 
as  an  end  in  itself.  Only  consider  what  the  position  of 
the  man  of  science  would  be,  if,  before  he  began  to  think, 
he  had  to  refute  all  the  philosophical  systems  one  by  one. 
Once  more,  there  is  no  such  thing  as  "the  philosophy  of 
Mach."1 

8.      L/ 

Whether  I  shall  ever  succeed  in  making  my  fundamental 
ideas  plausible  to  the  philosophers,  I  must  leave  to  time  to 
1  Cf.  Erkenntnis  und  It rtum,  1905,  Preface. 


THE  ANALYSIS  OF  SENSATIONS        369 

decide.  I  do  not  attach  much  importance  to  this  at 
present,  though  I  have  a  deep  reverence  for  the  gigantic 
intellectual  labors  of  the  great  philosophers  of  all  ages.  But 
I  have  an  honest  and  lively  desire  for  an  understanding  with 
the  natural  scientists,  and  I  consider  that  such  an  under- 
standing is  attainable.  I  should  like  the  scientists  to 
realize  that  my  view  eliminates  all  metaphysical  questions 
indifferently,  whether  they  be  only  regarded  as  insoluble 
at  the  present  moment,  or  whether  they  be  regarded  as 
meaningless  for  all  time.  I  should  like  them,  further,  to 
reflect  that  everything  that  we  can  know  about  the  world  is 
necessarily  expressed  in  the  sensations,  which  can  be  set 
free  from  the  individual  influence  of  the  observer  in  a 
precisely  definable  manner  (p.  344  above).  Everything  that 
we  can  want  to  know  is  given  by  the  solution  of  a  problem 
in  mathematical  form,  by  the  ascertainment  of  the  functional 
dependence  of  the  sensational  elements  on  one  another. 
This  knowledge  exhausts  the  knowledge  of  "reality."  The 
bridge  between  physics,  in  the  widest  sense,  and  scientific 
psychology,  is  formed  of  these  very  elements,  which  are 
physical  and  psychical  objects  according  to  the  kind  of 

combination  that  is  being  investigated. 

A7  SI      £• 


Probably  a  good  many  physiologists  have  taken  objection 
to  a  point  of  detail  in  my  position,  as  to  which  I  should 
like  to  say  something  more.  I  have  a  great  value  for  re- 
searches such  as  those  of  S.  Exner,1  and  I  believe  that 

1  Entwurf  zu  einer  physiologischen  Erkldrung  der  psychischen 
Erscheinungen,  Vienna,  1894. 


370        THE  ANALYSIS  OF  SENSATIONS 

many  important  problems  as  to  psychical  phenomena  can 
be  solved  merely  by  the  investigation  of  the  nervous  con- 
nexions of  the  central  organs,1  and  by  observation  of  the 
way  in  which  stimuli  are  arranged  in  a  quantitative  scale.2 
Indeed  Exner's  book  itself  is  evidence  of  this.  But  I  feel 
that  the  main  problems  still  remain  unsolved.  For,  from 
my  point  of  view,  I  cannot  conceive,  any  more  than  I  could 
nearly  forty  years  ago,  how  the  qualitative  variety  of  sensa- 
tions can  arise  from  the  variation  of  the  connexions  and 
from  mere  quantitative  differences.  Fechner's  psycho- 
physics,  which  have  had  so  important  an  influence,  did 
not  fail  to  stimulate  me  exceedingly  at  the  time.  Inspired 
by  Fechner's  book,  I  delivered  some  very  bad  lectures  on 
the  subject,  the  value  of  my  lectures  being  still  further 
diminished  by  the  fact  that  I  soon  came  to  see  that  Fechner's 
theory  of  formulae  of  measurement  was  erroneous.  In  this 
connexion,  after  explaining  Helmholtz's  "  telegraph-wire " 
theory  of  sensation,  I  said  :  "  But  will  the  electric  processes 
in  the  nerves  prove  to  be  too  simple  to  explain  adequately 
the  difference  of  quality  in  sensations  ?  Will  it  be  necessary 
to  thrust  the  explanation  further  back  into  regions  that  are 
still  unknown  ?  What  if,  after  investigating  the  whole  brain, 
we  find  everywhere  nothing  but  electric  currents?  My 
personal  opinion  is  this.  The  electrical  researches  that 
have  been  made  on  the  nerves  are  no  doubt  of  a  very 
delicate  nature,  but  in  one  respect  they  are  very  rough. 
An  electric  current  of  given  intensity  tells  us  nothing, 
except  that  a  definite  quantity  of  living  force  passes  in  the 
time-unit  through  a  cross-section  of  the  current.  By  what 

1  Entiuurf  zu  einer physiologischen  Erklarwng  der  psychischen  Erschei- 
nungen,  p.  4,  Vienna,  1894.  2  Op.  cit.>  p.  3. 


THE  ANALYSIS  OF  SENSATIONS        371 

processes  and  by  what  molecular  movements  that  living 
force  is  assisted,  we  do  not  know.  It  is  possible  that  the 
most  diverse  processes  underlie  one  and  the  same  intensity 
of  current."1  Even  to-day  I  have  not  succeeded  in  getting 
rid  of  this  idea,  and  I  cannot  refrain  from  bringing  forward 
evidence  that  confirms  it  in  essentially  the  same  form,  as 
for  instance  by  referring  to  the  presence  of  an  identical 
current  in  different  electrolytes.2  The  progress  of  physio- 
logical chemistry,3  and  the  experiments  that  have  been  made 
in  the  transplantation  of  different  organs,4  seem  to  me  to-day 
to  be  still  more  decisively  in  favor  of  my  view.  Rollett 5 
has  brought  into  connexion  with  one  another,  and  discussed 
in  a  very  instructive  manner,  with  reference  both  to  his  own 
work  and  to  that  of  others,  a  number  of  important  questions 
closely  related  to  the  discussions  of  this  book. 

1  "  Vorlesungen    iiber    Psychophysik,"    Zeitschrijt  fiir  praktische 
Heilkunde,  pp.  335,  336,  Vienna,  1863. 

2  See  the  preface  to   the  preceding  English  edition  of  this  book, 
Chicago,  1897,  pp.  v,  vi. 

3  Huppert,  Ueber  die  Erhaltung  der  Arteigenschaften,  Prague,  1896. 

4  Ribbert,    "  Ueber   Transplantation   von    Ovarium,    Hoden,    und 
Mamma,"  Archivfur  Entioicklungsmechanik,  1898,  Vol.  VII. 

5  "  Entwicklungslehre  und   spezifische   Energie,"  Mittcihtngen  des 
Vereins  der  Aerzte  in  Steiermark^  1902,  No.  8. 


INDEX 


I 


INDEX  OF  SUBJECTS 


Abstraction,  what  is  it  ?  325 
Adaptation,  mental,  328,  365 
Acceleration,  sensation  of,  133, 
139  sqq. 

—  organ  reacting  on,  165 
Accommodation    of    the    eye, 

how  effected,  228  sqq. 
After-images,  131,  252 
Animals,  asymmetry  in,  113 

—  intelligence  of  exaggerated, 

196 

—  reflex    movements    in,    171 

sqq.,  196,  198 

—  measurement  of  time  by,  250 
Animism,  97 
Anthropomorphism,  97 

Ants,  78  n. 

Apoplectic  stroke,  effect  of,  on 

author,  175 

Art,  symmetry  in,  117  sqq. 
Association,  100,  174,  235-244, 

264 

—  inertia  of,  253 
Astronomers,  personal  equation 

of,  251 

Asymmetry,  112 
Attention,  178  sqq. 
Atoms,  311 


Biology,    connexion    of,    with 

physics,  84  sqq. 
Blind,  the,  space-sensations  of, 

118,  135,  139,  180,  187 


Bodies,        permanency        and 

rigidity  of,   191 
"  Body,"  what  is  it  ?    13,   32, 

329,  330 


|  Cats,  experiments  on,  159 
Causal   explanations,    meaning 

of,  335-338 
Causality,  85  sqq. 
\  Change,  351 

Chick,  the,  126,  171,  179,  188 
Color-adaptation,  95 
Color-sensations,     64-69,     103 
sqq. 

—  connexion    of,   with    space- 

sensations,  105 

"  Concealed  movements,"  313 
Concepts,  what  are  they  ?  321- 

327 

—  physical,  364 
Congruence,  346 

—  geometrical  and  optical,  107 
Consciousness,  organ  of,  257 
Conservation  of  energy,  55  n. 
Consonance,  272  sqq. 
Consumption,     organic,      con- 
nexion    of,     with     time- 
sensation,  256 

Continuity,    principle    of,    57, 

319 

Crustacea,  experiments  on,  157 
Cyclostat,  149 


2  A 


373 


374 


INDEX 


D  Frog,  reflex  movements  in  the, 

97,  158,  183,  241 
Deaf-mutes,     vertigo    in,     159    Function,  notion  of,  in  physics 

sqq.  and  biology,  93 

Doves,  experiments  on,  158         i  —  mathematical     concept     of, 
Dreams,  u,  253-255,  281  363 

—  anachronisms  in,  253  Functional  relations,  35 


Ear,    middle,    function   of,    in 

hearing,  299  sqq. 
Echidna,  164 

Economy  of  thought,  49,  328 
Ego,  the,  apparent  permanency 


self  -inspection  of,  20 
•  --  not  primary,  23 
--  impermanence     of,     357 

sqq. 

Egyptian  drawings,  232 
Electricity,  93 
Elements    (sensations),    8   sqq., 

1  3*??.,  35 
--  dependence    of,  on    one 

another,  344 

Embryology,  experimental,  95 
Emotions,  21 

—  influence  of,  on  time-sensa- 

tion, 261 
Energy,  341 
Equilibrium,  function  of  laby- 

rinth of    the    ear  in,    162 

sqa, 
Evolution,      bearing     of,      on 

physiology,  71  sqq. 

—  theory    of,    as     scientific 
hypothesis,  79 

Eye,  motor  apparatus  of,  no 
sqq. 

—  experiments  with  the,  128 

—  reflex    movements    of    the, 

132  sqq. 


Force,  341 

Freedom  of  the  will,  351 


Galvanotropic  reaction,  159 
Genius,  definition  of,  308 
I  Geometrical    space,    120,    168, 

181,  345 
Geometry,   Greek  and  Indian, 

1 20 

i  Ghosts,  fear  of,  75 
i  Guinea-pigs,  behaviour  of,  when 
deprived  of  labyrinths,  161 
sqq. 


H 


Harmony,  function  of  contrast 

in,  288 

Hawk-moth,  85 
;  Hearing,  Helmholtz'  theory  of, 

266  sqq. 
i  —  author's  suggested  theory  of, 

291  sqq. 

|  —  Ewald's  theory  of,  301 
i  Heredity,  72,  77,  308 
Heterodromous    processes,    68, 

253 

Homodromous  processes,  68 
Horopter,  Miiller's,  125 
i  Horses,  deficiency  of,  in  sense 

of  time,  260 


Idealism,  357,  362,  367 
Illusions,  explanation  of,  1 1 

—  visual,     202-208,     220-231, 

2343  255 

—  auditory,  255 

;  Images,  mental,  200 


INDEX 


375 


Images,     mental,    how    deter- 
mined, 201  sqq. 
Immortality,  25 
Impulses,  innate,  239 
Innervation,  173-176  sqq. 

—  and  the  will,  165-167 

—  of  muscles  of  the  eye,  169 
Insects,  retina  of,  228 
Intellect,  definition  of,  196 
Intervals,  musical,  285-287 
sensations  connected  with, 

289  sqq. 

I ntr ejection,  28,  51  sqq. 
Intuitive  knowledge,  319,  327, 

328 
Inversion,  optical,  223  sqq. 


Judgment,  process  of,  317  sq. 


Labyrinth  of  the  ear,  function 

of,  154  sqq. 
Light,  electro-magnetic  theory 

of,  104 
—  distribution  of,  on  the  retina, 

217 


M 


Matter,  not  immutable,  312 

—  =     combination     of     sen- 
sations, 331 

Measurement,  standards  of,  192 

—  absolute,  342 
Mechanical  systems,  90 
Membranes,    vibration    of,    in 

fluids,  299  sqq. 
Memory,  235-244 

—  Hering's  theory  of,  72 
Memory-images,  172 
Memory-traces,  analogy  of,  to 

physical  traces,  236 
Mice,  Japanese,  deafness  in,  160 
Millipede,  188 


Mole,  equilibrium  and  hearing 

in  the,  162  sq. 
Moment,  320 
Motor  sensations,  139  sqq.,  146, 

!73 
Mouse,  blind,  equilibrium  and 

hearing  in,  162 
Music,  physiological  origin  of, 

263 

—  relation  of  speech  to,  280  sq. 

—  modern  development  of,  307 
Musical       tones,       Helmholtz' 

analysis  of,  265  sqq. 


N 


Nervous  system,  interaction  of 

parts  of,  241 
Numbers,  theory  of,  dependent 

on  physics,  346 
Nystagmus,  158 


Optical  space,  168 

Organisms,  peculiar  charac- 
teristics of,  98  sqq. 

—  plasticity  of,  238 

Otolithic  apparatus,  the,  153 
sqq. 


Painting,  347 

—  Italian,  233 

—  Pompeian,  232 

Pan-psychism,  362 

Perspectives,  optical  pheno- 
mena connected  with,  212 
sqq.,  220  sqq.,  232 

Physical  and  psychical,  the, 
connexion  between,  17,  22 

the,  view  of  relation  be- 
tween, identical  in  Mach 
and  Avenarius,  51  sqq. 

the,  parallelism  of,  60 

the,  dualism  of,  141  sqq. 


376 


INDEX 


Physics,  bearing  of  physiology 
and   psychology  on,   Bio- 
Physics  and  biology,  connexion 

between,  84  sqq. 
Pigeons,  reflex  movements  in, 

73 

Planetary  motions,  the,  336 
Pleasure  and  pain,  21 
Plethysmography,  257 
Pseudoscopy,  225 
Puzzle-pictures,  212 


R 


Reflex  movements  in  animals,  1 

7.3  sqq. 
Relative  motion,  sensations  of,  : 

142  sqq. 
Representation,  257 

—  sensations  supplemented  by,  ! 

199 
Resonance-theory    of    hearing, 

269  sqq.,  303 
Retina,  the,  122  sqq. 

—  movement  of  images  on,  144  • 
Retinas,  "  synergy  "  of,  123 
Rhythm,  no  symmetry  in,  256    \ 
Rhythms,  identity  of,  258  sqq.     \ 
Right  and  left,  distinction  of,  j 

ii2,  339 

Rotation,  phenomena  of,  134,  ! 
138  sq.,  140  sqq.,  149  sqq., 
158 


Semicircular    canals,    the,    149 

sqq. 
Sensations,  direction  of,  109 

—  specific,  184 

—  lower  limit  of,  243 

—  sexual,  263 

Sheep,  experiments  on,  154 
Sight-sensations,  195-234 
Silk- worms,  76 


Similarity,    optical    and    geo- 
metrical, 108  sqq.,  115 
Solipsism,  36,  37,  358,  359 
Sound-color,  269 
Sounds,  analysis  of,  262-309 
Space,  339 

—  physiological  and  geometri- 

cal properties  of,  120 

—  visual  and  conceptual,  124 

—  optical  and  geometrical,  168 

—  geometrical,  contrasted  with 

physiological,  181  sqq. 

—  Euclidean,  182 

—  tactual,  1 86 

—  tactual   and   optical   homo- 

geneous, 187 

—  analogy    of,   to  tone-sensa- 

tion, 278,  282  sqq. 

—  geometrical,  345 

—  and  time,    functional   inter- 

dependence of,  348 
Sparrow,  74,  171,  196 
Species,  preservation  of,  81 
Specific  energies,  122  sqq.,  275 
Specific    sense  -  energies,    prin- 
ciple of,  165 

Subject  and  object,  341,  365 
Substance,  what  is  it  ?  328,  333 
Sufficient  differentiation,  prin- 
ciple of,  58,  319 
Symmetry,  106,  108,  in,  114, 
H5  sq. 

—  in  music,  272  n. 

—  sense  of,  170 


Teleology,  80,  83-101 
Temperature,  how  determined, 

35° 

"  Thing-in-itself,"  6,  361  n. 
"  Thought-experiment,"  194 
Time,  perspectival  contraction 

of,  258 

—  dependent  on  our  sensibility, 

330 

—  physical,  349 

—  irreversibility  of,  351 
Time-sensation,  244-261 


INDEX 


377 


Tones,  fusion  of,  274 
Tone-sensations,  262-309 
Touch,  sensations  of,  135  sqq. 
Tropisms,  241 


U 

Unity  of  consciousness,  27-29 
Unity    of    the    physical    and 
psychical,  339 


Vertigo,  optical,  138 

—  in  deaf-mutes,  148  sqq. 


Vertigo,  galvanic,  159  sqq. 
—  rotatory,*  5  9  sqq. 
Vestibular  apparatus,  the,  154 
Vision,  binocular,  125 


W 

Will,  the,  23,  100,  171-180 

connexion  of,  with  inner- 

vations,  129 

to  move,  sensations  con- 
nected with,  139 

connexion  of,  with  music, 

262 

freedom  of,  351 


II 
INDEX   OF  NAMES 


Abraham,  268  n. 
Ach,  158 

Allen,  Grant,  103  n. 
Alexander,  160-163 
Aristotle,  84,  87,  136  n. 
Aubert,  66 
Auerbach,  268  n. 
Autenrieth,  85 

Avenarius,  27  n.,  30  n.,  46-56, 
261,  354.  362. 


Bain,  173 
Benndorf,  103  n. 
Beer,  197  n.,  230 
Berg,  263 

Berkeley,  48,  135  «.,  361,  367 
Bernoulli,  J.,  121 
Bethe,  196,  197  n. 
Biehl,  154 
Boyle,  174 

Breuer,  131,  132,  137,  140,  153, 
X54»  155.  159,  162,  163,  164 


Brewster,  63,  64  n.,  174  n 
Bridgman,  Laura,  323,  324 
Brown,  Crum,  133,  144,  148 
Briicke,  123,  268  n. 
Briihl,  268  n. 
Buttel-Reepen,  197 


Carus,  Paul,  356  n. 
Chesselden,  136  n. 
Comte,  46 

Cornelius,  H.,  48,  363 
Cornelius,  P.,  286 
Cossmann,  89  n. 
Cyon,  164 

D 

D'Alembert,  272  n. 

Darwin,  49,  71,  74,  76,  79,  81, 

104  n.,  241,.  263 
Delage,  155 

Descartes,  118,  122,  197 
Diderot,  135  n. 
Dove,  123 


378 


INDEX 


Dreyfuss,  161 
Driesch,  80,  98 
Dubois-Reymond,  313 
Du  Prel,  255 
Dvorak,  251,  252,  268  n. 


Emch,  119 

Euclid,  168,  181,  190,  191  n. 
Euler,  272  n.,  273  n.,  290,  307 
Ewald,  149,  153,  158,  164,  241, 

301,  302,  303 
Exner,  145,  228  n.,  230,  268  n,, 

369 


Fechner,  61,  81  n.,  101  n.,  210, 

251  n,,  264  n. 
Fischer,  265  n. 
Forel,  197 
Fourier,  269 

Fraunhofer,  7,  65  n.t  316 
Friesach,  302 


Gay-Lussac,  310 
Geissler,  252 
Goethe,  i 
Goltz,  74,  197,  241 
Gomperz,  326,  327 
Govi,  122  n.,  149 
Graber,  292  n. 
Grimaldi,  219 
Groth,  67 
Gruithuisen,  4  n. 
Guldberg,  112,  113 
Guye,  148 

H 

Haddon,  117 

Haga,  219  n. 

Hammerschlag,  160 

Hankel,  120 

Harvey,  86 

Hauptmann,  C.,  48,  61  n.,  89  n. 

Hauptmann,  M.,  272  n. 


Heidenhain,  in 

Heller,  136  n.,  137  n. 

Helmholtz,  63,  64  n.,  117,  126, 
173,  191  n.,  263,  265-275, 
291,  292,  297,  298,  299  «., 
301,  305,  306,  370 

Hensen,  88  n.,  292  n. 

Herakleitos,  368 
i  Herbart,  368 

i  Hering,  27  n.,  30  n.,  50,  65-69, 
72,  80  n.,  99  n.,  100  n.,  109, 
122  n.,  124,  125,  139,  168- 
170,  172,  177,  178,  181  n., 
183,  197  n.,  225,  277  n. 
\  Hermann,  245  n.,  269,  270,  271, 

303 
1  Hero,  87 

Herodotos,  321  n. 
\  Herzfeld,  67  n. 
|  Heymans,  61  n.,  226,  252  n. 
I  Hillebrand,     125    n.,     177    n.t 
221  n. 

Hirth,  99  n.,  136  n. 

Hofler,  55  n.,  226 

Honigswald,  367 

Holtz,  96  n.,  131 

Hume,  4  n.,  46,  356  n.,  368 

Huppert,  371  n. 


James,  21,  129,  144,  148,  159, 
163,  168  n.,  173,  175  n.t 
176,  179,  181  n.,  257,  310  «. 

Jerusalem,  318  n.,  323,  324  n. 

Jones,  116 

K 

Kant,  30  n.,  194.  325.  357'  361 

n.,  367 

Kepler,  86,  334,  336 
Kessel,  279  n. 
King,  174  n. 
Kirchhoff,  49 
Kohlrausch,  268  n. 
Konig,  269,  270 
Kornfeld,  257  n. 
Krause,  E.,  103  n. 
Krause,  C.  F.,  20  n. 


INDEX 


379 


Kreidl,  132,  153,  157,  159,  160, 

162,  163 

Kries,  von,  61  n.,  69  n.,  327 
Kiilke,  286 
Kiilpe,  61  n.,  89  n. 


Laplace,  313 
Leibniz,  191  n.,  273  n. 
Leonardo  da  Vinci,  66,  67,  206, 

287 

Lichtenberg,  28,  356  n. 
Lipps,  131  n.,  262  n.,  273  n. 
Lissajous,  232 
Locke,  135  n.,  318 
Loeb,  86,  98,  113,  137  n  ,  153, 

196,    221,    224,    226,    241, 

247  n. 

Loewy,  135  n. 
Lubbock,  149 
Ludwig,  66 


M 

Magnus,  103  n. 

Manacei'ne,  255 

Mariotte,  39,  310 

Marty,  103  n. 

Maxwell,  247  n. 

Mayer,  A.,  64 

Mayer,  J.  R.,  341 

Meinong,  346  n. 

Menger,  98 

Meumann,  245  n. 

Meyer,  270  «.' 

Meynert,  261 

Mill,  92,  335  n.,  363 

Moliere,  37,  119 

Molyneux,  135  n. 

Morgan,  76,  77 

Moser,  237 

Mosso,  257 

Munk,  135  n. 

Miiller,   27,  59,   122,   125,   126, 

202,  203 
Miinsterberg,  168  n.,  173,  176, 


Mygin 


245  n.,  252 
d,  159 


N 

Nagel,  132,  153,  155,  165 
Newton,  49,  64,  92,   121,   174, 

307,  334.  336,  337 
Nichols,  245  n. 
Nietzsche,  25 


Obermayer,  von,  219  n. 
Oettingen,  von,  271,  272,  275, 

297 

Ohm,  265 
Oppel,  144,  273  n. 
Ostwald,  99  n.,  239  n. 


Panum,  123,  126,  217,  229 

Pauli,  68,  69,  83  n.,  112  n.,  253 

Petzold,  36  n.,  48,  350,  351,  352 

Pfaundler,  268  n. 

Pfeffer,  94 

Plateau,  134,  144,  223 

Plato,  ii 

Polak,  273  n. 

Politzer,  299 

Pollak,  153,  159 

Polle,  103  n. 

Poncelet,  341 

Popper,  20  n.,  30  n. 

Poulton,  96  n. 

Prentiss,  157 

Preyer,  31  n. 

Ptolemy,  122 

Purkinje,  133,  186,  252 

R 

Rameau,  265 
Reimarus,  85 
Reinke,  98 
Ribbert,  371  n. 
Ribot,  4,  21,  326,  327 
Riehl,  31  n.,  139 
Riemann,  181 
Robert,  254 


38o 

Rollett,  73,  371 
Roux,  95,  99  n. 


INDEX 


Sachs,  86 

Sandford,  252 

Saunderson,  136  n. 

Sauveur,  265 

Schafer,  153,  158 

Schaik,  van,  88  n. 

Scheffler,  228 

Schlodtmann,  126  n. 

Schmidt,  6  n. 

Schnabel,  135  n. 

Schneider,  77 

Schopenhauer,  i,  82  ».,  262 

Schultz,  104  n. 

Schumann,  245  n. 

Schuppe,  6  n.,  36  n.,  46 

Schuster,  71 

Scripture,  206,  245  n. 

Seebeck,  290 

Seeliger,  219  n. 

Semon,  72  w. 

Smith,  Adam,  49 

Smith,  R.,  265 

Soret,  117,  118,  122,  136  n. 

Spencer,  71,  77 

Spinoza,  46 

Staudt,  von,  200 

Steiner,  200 

Stern,  324  n. 

Steinhauser,  265  «. 

Stohr,  227,  228,  229,  230,  303, 

318  w. 
Strauss,  75 
Strehl,  1 60 
Strieker,  280,  335  n. 
Stumpf,  61  n.,  126  n.,  262  n.t 

270  w.,  272,  273,  274,  290 

n.,  293,  298,  299 
Suess,  236 
Szily,  von,  146  n. 


Tolstoi,  112 
Tschermak,  126  n. 
Tylor,  52  n.,  56 

U 
Uexkiill,  197  w. 


Vergil,  104  n. 
Vierordt,  145 
Volkmann,  49 


W 

Wahle,  31  n. 

Wallaschek,    246    n..    255    n., 

260,  261,  309  w. 
Wasmann,  199 
Weber,  81  n.,  299 
Weismann,  24,  72,  73,  77,  78, 

308 

Wheatstone,  123 
Whitney,  322  n. 
Wilner/95 
Wind,  219  n. 
Witasek,  226  w. 
Wlassak,  50,  56,  181  n.,  261 
Wollaston,  65 
Wundt,  173 


Young,  64,  265,  269,  305,  341 


Zell,  96  n.,  197 
Ziegler,  240  «. 
Zindler,  346  n. 
Zollner,  225,  226 


TURNBULL   AND   SPEARS,  PRINTERS,   EDINBURGH 


